{"id":245,"date":"2026-07-21T20:11:07","date_gmt":"2026-07-21T20:11:07","guid":{"rendered":"https:\/\/squarefootcalc.com\/blog\/?p=245"},"modified":"2026-07-21T20:11:08","modified_gmt":"2026-07-21T20:11:08","slug":"square-footage-formula-every-common-shape","status":"publish","type":"post","link":"https:\/\/squarefootcalc.com\/blog\/square-footage-formula-every-common-shape\/","title":{"rendered":"Square Footage Formula for Every Common Shape (Rectangle, Triangle, Circle, L-Shape)"},"content":{"rendered":"\n<link href=\"https:\/\/fonts.googleapis.com\/css2?family=Playfair+Display:ital,wght@0,400;0,700;1,400&#038;family=Source+Serif+4:opsz,wght@8..60,300;8..60,400;8..60,600&#038;display=swap\" rel=\"stylesheet\">\n<style>\n  :root {\n    --ink: #1a1612;\n    --paper: #faf7f2;\n    --cream: #f2ede3;\n    --rust: #b84c2a;\n    --gold: #c9983a;\n    --teal: #2a7c72;\n    --muted: #6b6257;\n    --border: #d9d0c3;\n    --highlight: #fff8e8;\n  }\n\n  * { box-sizing: border-box; margin: 0; padding: 0; }\n\n  .subtitle { font-size: 1.1rem; color: var(--muted); line-height: 1.6; max-width: 640px; font-style: italic; margin-bottom: 8px; }\n  .divider { border: none; border-top: 1px solid var(--border); margin: 48px 0; }\n\n  h2 { font-family: 'Playfair Display', serif; font-size: 1.65rem; font-weight: 700; color: var(--ink); margin: 56px 0 16px; padding-bottom: 8px; border-bottom: 2px solid var(--gold); display: inline-block; }\n  h3 { font-family: 'Playfair Display', serif; font-size: 1.2rem; font-weight: 700; color: var(--ink); margin: 32px 0 12px; }\n\n  p { margin-bottom: 18px; font-size: 1rem; line-height: 1.75; color: var(--ink); }\n  a { color: var(--rust); text-decoration: none; }\n  a:hover { text-decoration: underline; }\n  strong { color: var(--ink); }\n\n  .toc { background: var(--cream); border: 1px solid var(--border); padding: 24px 28px; margin: 36px 0; border-radius: 3px; }\n  .toc-title { font-family: 'Playfair Display', serif; font-size: 0.95rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.1em; color: var(--muted); margin-bottom: 12px; }\n  .toc ol { padding-left: 20px; font-size: 0.95rem; color: var(--muted); }\n  .toc li { margin-bottom: 5px; }\n  .toc a { color: var(--muted); }\n  .toc a:hover { color: var(--rust); }\n\n  .formula-hero { background: var(--ink); color: white; border-radius: 4px; padding: 32px; margin: 32px 0; text-align: center; }\n  .formula-hero .label { font-family: 'Source Serif 4', serif; font-size: 0.78rem; letter-spacing: 0.18em; text-transform: uppercase; color: var(--gold); font-weight: 600; margin-bottom: 14px; }\n  .formula-hero .formula { font-family: 'Playfair Display', serif; font-size: 1.4rem; font-weight: 700; color: white; margin-bottom: 10px; line-height: 1.5; }\n  .formula-hero .note { font-size: 0.9rem; color: rgba(255,255,255,0.6); font-style: italic; }\n\n  .formula-box { background: var(--highlight); border-left: 3px solid var(--gold); padding: 14px 18px; margin: 20px 0; border-radius: 0 3px 3px 0; }\n  .formula-box .formula-label { font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.12em; color: var(--muted); font-weight: 600; margin-bottom: 6px; }\n  .formula-box .formula-text { font-family: 'Playfair Display', serif; font-size: 1.05rem; color: var(--ink); line-height: 1.6; }\n\n  .example-box { background: #f8faf9; border: 1px solid #c5d9d5; border-radius: 3px; padding: 14px 18px; font-size: 0.95rem; margin: 14px 0; color: var(--muted); line-height: 1.75; }\n  .example-box .ex-label { font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.12em; color: var(--teal); font-weight: 600; margin-bottom: 6px; }\n  .example-box .ex-answer { font-size: 1.15rem; font-weight: 700; color: var(--teal); margin-top: 6px; display: block; }\n\n  \/* MORE SHAPES CARDS (analogous to tile-grid) *\/\n  .tile-grid { display: grid; grid-template-columns: repeat(3,1fr); gap: 14px; margin: 28px 0; }\n  @media (max-width: 560px) { .tile-grid { grid-template-columns: 1fr 1fr; } }\n  .tile-card { background: white; border: 1px solid var(--border); border-radius: 3px; padding: 18px 12px; text-align: center; }\n  .tile-size { font-family: 'Playfair Display', serif; font-size: 1.05rem; font-weight: 700; color: var(--ink); margin-bottom: 4px; }\n  .tile-sqft { font-size: 0.95rem; font-weight: 700; color: var(--rust); font-family: 'Playfair Display', serif; }\n  .tile-note { font-size: 0.78rem; color: var(--muted); margin-top: 4px; line-height: 1.4; }\n\n  \/* SHAPE CARDS (analogous to pattern-card) *\/\n  .pattern-card { background: white; border: 1px solid var(--border); border-radius: 4px; padding: 32px; margin: 36px 0; box-shadow: 0 2px 12px rgba(0,0,0,0.04); position: relative; }\n  .pattern-card::before { content: attr(data-label); position: absolute; top: -14px; left: 28px; background: var(--rust); color: white; font-family: 'Playfair Display', serif; font-size: 0.78rem; font-weight: 700; letter-spacing: 0.12em; text-transform: uppercase; padding: 3px 12px; border-radius: 2px; }\n  .pattern-card.teal::before { background: var(--teal); }\n  .pattern-card.gold::before { background: var(--gold); }\n  .pattern-card.dark::before { background: #3a3530; }\n  .pattern-card h3 { font-size: 1.2rem; margin-top: 6px; margin-bottom: 6px; }\n  .pattern-meta { font-size: 0.9rem; color: var(--muted); margin-bottom: 20px; font-style: italic; }\n  .pattern-body { display: grid; grid-template-columns: 1fr 1fr; gap: 28px; align-items: start; }\n  @media (max-width: 580px) { .pattern-body { grid-template-columns: 1fr; } .pattern-card { padding: 24px; } }\n  .pattern-svg-wrap { display: flex; justify-content: center; align-items: center; background: var(--cream); border-radius: 4px; padding: 16px; min-height: 180px; }\n  .pattern-svg-wrap svg { max-width: 100%; height: auto; display: block; }\n\n  .callout { background: var(--cream); border: 1px solid var(--border); border-radius: 4px; padding: 24px 28px; margin: 32px 0; }\n  .callout-title { font-family: 'Playfair Display', serif; font-size: 1.05rem; font-weight: 700; color: var(--ink); margin-bottom: 16px; }\n\n  table { width: 100%; border-collapse: collapse; margin: 28px 0; font-size: 0.95rem; }\n  thead tr { background: var(--ink); color: white; }\n  thead th { padding: 12px 16px; text-align: left; font-family: 'Source Serif 4', serif; font-weight: 600; font-size: 0.82rem; letter-spacing: 0.08em; text-transform: uppercase; }\n  tbody tr:nth-child(even) { background: var(--cream); }\n  tbody tr:nth-child(odd) { background: white; }\n  tbody td { padding: 11px 16px; border-bottom: 1px solid var(--border); color: var(--muted); }\n  tbody td:first-child { font-weight: 600; color: var(--ink); }\n\n  .tips-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin: 24px 0; }\n  @media (max-width: 520px) { .tips-grid { grid-template-columns: 1fr; } }\n  .tip-card { background: white; border: 1px solid var(--border); border-radius: 3px; padding: 18px 20px; }\n  .tip-card .tip-icon { font-size: 1.4rem; margin-bottom: 8px; }\n  .tip-card strong { display: block; color: var(--rust); margin-bottom: 4px; font-size: 0.88rem; letter-spacing: 0.05em; text-transform: uppercase; }\n  .tip-card p { margin: 0; color: var(--muted); line-height: 1.5; font-size: 0.93rem; }\n\n  .diagram-wrap { margin: 32px 0; background: var(--cream); border: 1px solid var(--border); border-radius: 4px; padding: 20px; overflow-x: auto; }\n  .diagram-wrap svg { display: block; margin: 0 auto; max-width: 100%; }\n\n  .examples-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; margin: 28px 0; }\n  @media (max-width: 540px) { .examples-grid { grid-template-columns: 1fr; } }\n  .ex-card { background: white; border: 1px solid var(--border); border-radius: 4px; padding: 22px 20px; position: relative; }\n  .ex-card::before { content: attr(data-room); position: absolute; top: -13px; left: 16px; background: var(--gold); color: white; font-family: 'Source Serif 4', serif; font-size: 0.74rem; font-weight: 700; letter-spacing: 0.1em; text-transform: uppercase; padding: 3px 10px; border-radius: 2px; }\n  .ex-card h3 { font-size: 1.05rem; margin: 6px 0 10px; color: var(--ink); }\n  .ex-step { display: flex; gap: 10px; align-items: baseline; margin-bottom: 7px; font-size: 0.93rem; color: var(--muted); }\n  .ex-arrow { color: var(--gold); font-weight: 700; flex-shrink: 0; }\n  .ex-result { margin-top: 14px; background: #f8faf9; border: 1px solid #c5d9d5; border-radius: 3px; padding: 10px 14px; font-size: 1rem; font-weight: 700; color: var(--teal); }\n\n  .faq { margin: 24px 0; }\n  .faq-item { border-top: 1px solid var(--border); padding: 20px 0; }\n  .faq-q { font-family: 'Playfair Display', serif; font-size: 1.05rem; font-weight: 700; color: var(--ink); margin-bottom: 8px; }\n  .faq-a { color: var(--muted); font-size: 0.97rem; line-height: 1.7; margin: 0; }\n\n  .cta-box { background: var(--ink); color: white; border-radius: 4px; padding: 28px 32px; margin: 48px 0 24px; text-align: center; }\n  .cta-box p { color: rgba(255,255,255,0.75); margin-bottom: 16px; font-size: 0.97rem; }\n  .cta-btn { display: inline-block; background: var(--rust); color: white; font-family: 'Source Serif 4', serif; font-weight: 600; font-size: 0.9rem; letter-spacing: 0.06em; text-transform: uppercase; padding: 12px 28px; border-radius: 2px; text-decoration: none; }\n  .cta-btn:hover { background: #9e3e22; text-decoration: none; }\n<\/style>\n\n<!-- INTRO -->\n<header>\n  <p class=\"subtitle\">Length times width only gets you through the simplest rooms. The moment a space has a curve, an angle, or an L-shaped floor plan, that one formula stops working \u2014 and you need the right one for the actual shape in front of you. Here&#8217;s every formula you&#8217;re likely to need, in one place.<\/p>\n<\/header>\n\n<div class=\"toc\">\n  <div class=\"toc-title\">In this guide<\/div>\n  <ol>\n    <li><a href=\"#rectangle\">Rectangle<\/a><\/li>\n    <li><a href=\"#triangle\">Triangle<\/a><\/li>\n    <li><a href=\"#circle\">Circle<\/a><\/li>\n    <li><a href=\"#l-shape\">L-Shape<\/a><\/li>\n    <li><a href=\"#more-shapes\">More shapes at a glance<\/a><\/li>\n    <li><a href=\"#examples\">Worked examples<\/a><\/li>\n    <li><a href=\"#reference\">Quick reference table<\/a><\/li>\n    <li><a href=\"#mistakes\">Mistakes to avoid<\/a><\/li>\n    <li><a href=\"#faq\">Frequently asked questions<\/a><\/li>\n  <\/ol>\n<\/div>\n\n<p>Every shape&#8217;s area formula comes from the same underlying idea \u2014 covering a surface completely, without gaps or overlaps \u2014 but the arithmetic looks different depending on the shape&#8217;s geometry. Get the right formula for your specific shape and the calculation itself is always simple.<\/p>\n\n<p>Want the answer without doing the math by hand? <a href=\"https:\/\/squarefootcalc.com\/\">SquareFootCalc.com<\/a> calculates all of these shapes instantly \u2014 just enter your measurements.<\/p>\n\n<hr class=\"divider\" id=\"rectangle\">\n\n<!-- RECTANGLE -->\n<div class=\"pattern-card\" data-label=\"Shape 01\">\n  <h3>Rectangle<\/h3>\n  <div class=\"pattern-meta\">The most common room shape, and the formula everything else gets compared against<\/div>\n  <div class=\"pattern-body\">\n    <div class=\"pattern-svg-wrap\">\n      <svg viewBox=\"0 0 220 180\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"220\" height=\"180\">\n        <rect x=\"30\" y=\"30\" width=\"160\" height=\"100\" fill=\"#f5ede0\" stroke=\"#b84c2a\" stroke-width=\"2\"\/>\n        <text x=\"110\" y=\"20\" text-anchor=\"middle\" font-family=\"'Source Serif 4', serif\" font-size=\"10\" fill=\"#8a5a2e\">Length<\/text>\n        <text x=\"15\" y=\"85\" text-anchor=\"middle\" font-family=\"'Source Serif 4', serif\" font-size=\"10\" fill=\"#8a5a2e\" transform=\"rotate(-90 15 85)\">Width<\/text>\n        <text x=\"110\" y=\"85\" text-anchor=\"middle\" font-family=\"'Playfair Display', serif\" font-size=\"14\" font-weight=\"700\" fill=\"#8a5a2e\">L \u00d7 W<\/text>\n      <\/svg>\n    <\/div>\n    <div>\n      <div class=\"formula-box\">\n        <div class=\"formula-label\">Formula<\/div>\n        <div class=\"formula-text\">Length \u00d7 Width = Area<\/div>\n      <\/div>\n      <p style=\"font-size:0.95rem; color:var(--muted); margin-bottom:14px;\">The formula behind nearly every room-specific guide on this site. Measure two perpendicular sides and multiply \u2014 no adjustments needed for a true rectangle.<\/p>\n      <div class=\"example-box\">\n        <div class=\"ex-label\">12 ft \u00d7 10 ft room<\/div>\n        <span class=\"ex-answer\">= 120 square feet<\/span>\n      <\/div>\n    <\/div>\n  <\/div>\n<\/div>\n\n<hr class=\"divider\" id=\"triangle\">\n\n<!-- TRIANGLE -->\n<div class=\"pattern-card teal\" data-label=\"Shape 02\">\n  <h3>Triangle<\/h3>\n  <div class=\"pattern-meta\">Common in attic spaces, gable walls, and any room with an angled wall<\/div>\n  <div class=\"pattern-body\">\n    <div class=\"pattern-svg-wrap\">\n      <svg viewBox=\"0 0 220 180\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"220\" height=\"180\">\n        <polygon points=\"110,30 30,140 190,140\" fill=\"#e8f2f0\" stroke=\"#2a7c72\" stroke-width=\"2\"\/>\n        <line x1=\"110\" y1=\"30\" x2=\"110\" y2=\"140\" stroke=\"#2a7c72\" stroke-width=\"1\" stroke-dasharray=\"4,3\"\/>\n        <text x=\"110\" y=\"20\" text-anchor=\"middle\" font-family=\"'Source Serif 4', serif\" font-size=\"10\" fill=\"#1a5147\">Apex<\/text>\n        <text x=\"125\" y=\"90\" text-anchor=\"middle\" font-family=\"'Source Serif 4', serif\" font-size=\"9\" fill=\"#1a5147\">height<\/text>\n        <text x=\"110\" y=\"158\" text-anchor=\"middle\" font-family=\"'Source Serif 4', serif\" font-size=\"10\" fill=\"#1a5147\">base<\/text>\n      <\/svg>\n    <\/div>\n    <div>\n      <div class=\"formula-box\" style=\"border-left-color:var(--teal);\">\n        <div class=\"formula-label\">Formula<\/div>\n        <div class=\"formula-text\">(Base \u00d7 Height) \u00f7 2 = Area<br>Height is measured perpendicular to the base, not along a slanted side<\/div>\n      <\/div>\n      <p style=\"font-size:0.95rem; color:var(--muted); margin-bottom:14px;\">The division by 2 accounts for the triangle being exactly half of the rectangle that would enclose it. The trickiest part is measuring height correctly \u2014 it has to run straight up from the base at a right angle, not along the slanted edge.<\/p>\n      <div class=\"example-box\">\n        <div class=\"ex-label\">14 ft base, 8 ft height<\/div>\n        (14 \u00d7 8) \u00f7 2 = <span class=\"ex-answer\">56 square feet<\/span>\n      <\/div>\n    <\/div>\n  <\/div>\n<\/div>\n\n<hr class=\"divider\" id=\"circle\">\n\n<!-- CIRCLE -->\n<div class=\"pattern-card gold\" data-label=\"Shape 03\">\n  <h3>Circle<\/h3>\n  <div class=\"pattern-meta\">Round rooms, circular patios, and curved features \u2014 the only shape on this list using \u03c0<\/div>\n  <div class=\"pattern-body\">\n    <div class=\"pattern-svg-wrap\">\n      <svg viewBox=\"0 0 220 180\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"220\" height=\"180\">\n        <circle cx=\"110\" cy=\"90\" r=\"70\" fill=\"#fff8e8\" stroke=\"#c9983a\" stroke-width=\"2\"\/>\n        <line x1=\"110\" y1=\"90\" x2=\"180\" y2=\"90\" stroke=\"#8a5a2e\" stroke-width=\"1.5\"\/>\n        <circle cx=\"110\" cy=\"90\" r=\"3\" fill=\"#8a5a2e\"\/>\n        <text x=\"145\" y=\"82\" text-anchor=\"middle\" font-family=\"'Source Serif 4', serif\" font-size=\"10\" fill=\"#8a5a2e\">radius<\/text>\n      <\/svg>\n    <\/div>\n    <div>\n      <div class=\"formula-box\" style=\"border-left-color:var(--gold);\">\n        <div class=\"formula-label\">Formula<\/div>\n        <div class=\"formula-text\">\u03c0 \u00d7 Radius\u00b2 = Area<br>Radius is half the diameter \u2014 measure across the full circle and divide by 2 if that&#8217;s easier<\/div>\n      <\/div>\n      <p style=\"font-size:0.95rem; color:var(--muted); margin-bottom:14px;\">Using \u03c0 \u2248 3.14159 is accurate enough for nearly any practical purpose. The most common error is plugging in the diameter instead of the radius \u2014 square the wrong number and the result comes out roughly four times too large.<\/p>\n      <div class=\"example-box\">\n        <div class=\"ex-label\">Circle with 8 ft radius<\/div>\n        3.14159 \u00d7 8\u00b2 = 3.14159 \u00d7 64 = <span class=\"ex-answer\">201.06 square feet<\/span>\n      <\/div>\n    <\/div>\n  <\/div>\n<\/div>\n\n<hr class=\"divider\" id=\"l-shape\">\n\n<!-- L-SHAPE -->\n<div class=\"pattern-card dark\" data-label=\"Shape 04\">\n  <h3>L-Shape<\/h3>\n  <div class=\"pattern-meta\">Not a formula of its own \u2014 split into two rectangles and add the results together<\/div>\n  <div class=\"pattern-body\">\n    <div class=\"pattern-svg-wrap\">\n      <svg viewBox=\"0 0 220 180\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"220\" height=\"180\">\n        <path d=\"M30 30 L140 30 L140 90 L190 90 L190 150 L30 150 Z\" fill=\"#e8e2d5\" stroke=\"#3a3530\" stroke-width=\"2\"\/>\n        <line x1=\"140\" y1=\"30\" x2=\"140\" y2=\"150\" stroke=\"#3a3530\" stroke-width=\"1\" stroke-dasharray=\"4,3\"\/>\n        <text x=\"85\" y=\"95\" text-anchor=\"middle\" font-family=\"'Source Serif 4', serif\" font-size=\"10\" fill=\"#3a3530\">Section A<\/text>\n        <text x=\"165\" y=\"125\" text-anchor=\"middle\" font-family=\"'Source Serif 4', serif\" font-size=\"10\" fill=\"#3a3530\">Section B<\/text>\n      <\/svg>\n    <\/div>\n    <div>\n      <div class=\"formula-box\" style=\"border-left-color:#3a3530;\">\n        <div class=\"formula-label\">Formula<\/div>\n        <div class=\"formula-text\">Section A (L \u00d7 W) + Section B (L \u00d7 W) = Total Area<br>Draw one straight dividing line to turn the L into two rectangles<\/div>\n      <\/div>\n      <p style=\"font-size:0.95rem; color:var(--muted); margin-bottom:14px;\">Every L-shaped room is really two rectangles that happen to share an edge. Pick the most natural place to split it \u2014 usually where one wall&#8217;s length changes \u2014 measure each rectangle, and add the two areas together.<\/p>\n      <div class=\"example-box\">\n        <div class=\"ex-label\">Section A: 12\u00d78 ft, Section B: 6\u00d710 ft<\/div>\n        96 + 60 = <span class=\"ex-answer\">156 square feet<\/span>\n      <\/div>\n    <\/div>\n  <\/div>\n<\/div>\n\n<hr class=\"divider\" id=\"more-shapes\">\n\n<h2>More Shapes at a Glance<\/h2>\n\n<div class=\"tile-grid\">\n  <div class=\"tile-card\">\n    <div class=\"tile-size\">Square<\/div>\n    <div class=\"tile-sqft\">Side\u00b2<\/div>\n    <div class=\"tile-note\">A special case of a rectangle where all sides are equal<\/div>\n  <\/div>\n  <div class=\"tile-card\">\n    <div class=\"tile-size\">Trapezoid<\/div>\n    <div class=\"tile-sqft\">\u00bd \u00d7 (a + b) \u00d7 h<\/div>\n    <div class=\"tile-note\">Average the two parallel sides, multiply by the height between them<\/div>\n  <\/div>\n  <div class=\"tile-card\">\n    <div class=\"tile-size\">Parallelogram<\/div>\n    <div class=\"tile-sqft\">Base \u00d7 Height<\/div>\n    <div class=\"tile-note\">Same as a rectangle, but height is measured perpendicular to the base, not along the slanted side<\/div>\n  <\/div>\n  <div class=\"tile-card\">\n    <div class=\"tile-size\">Ellipse<\/div>\n    <div class=\"tile-sqft\">\u03c0 \u00d7 a \u00d7 b<\/div>\n    <div class=\"tile-note\">a and b are the two radii \u2014 half the long axis and half the short axis<\/div>\n  <\/div>\n  <div class=\"tile-card\">\n    <div class=\"tile-size\">Semi-Circle<\/div>\n    <div class=\"tile-sqft\">(\u03c0 \u00d7 Radius\u00b2) \u00f7 2<\/div>\n    <div class=\"tile-note\">Half of a full circle&#8217;s area \u2014 common for rounded room additions<\/div>\n  <\/div>\n  <div class=\"tile-card\">\n    <div class=\"tile-size\">Regular Hexagon<\/div>\n    <div class=\"tile-sqft\">(3\u221a3 \u00f7 2) \u00d7 Side\u00b2<\/div>\n    <div class=\"tile-note\">Less common in rooms, more common in tile and paver patterns<\/div>\n  <\/div>\n<\/div>\n\n<hr class=\"divider\" id=\"examples\">\n\n<h2>Worked Examples<\/h2>\n\n<div class=\"examples-grid\">\n  <div class=\"ex-card\" data-room=\"Rectangle\">\n    <h3>Living room, 16 \u00d7 13 ft<\/h3>\n    <div class=\"ex-step\"><span class=\"ex-arrow\">\u2192<\/span> 16 \u00d7 13<\/div>\n    <div class=\"ex-result\">208 square feet<\/div>\n  <\/div>\n  <div class=\"ex-card\" data-room=\"Triangle\">\n    <h3>Attic gable end, 20 ft base, 9 ft height<\/h3>\n    <div class=\"ex-step\"><span class=\"ex-arrow\">\u2192<\/span> (20 \u00d7 9) \u00f7 2<\/div>\n    <div class=\"ex-result\">90 square feet<\/div>\n  <\/div>\n  <div class=\"ex-card\" data-room=\"Circle\">\n    <h3>Round patio, 6 ft radius<\/h3>\n    <div class=\"ex-step\"><span class=\"ex-arrow\">\u2192<\/span> 3.14159 \u00d7 6\u00b2<\/div>\n    <div class=\"ex-result\">113.10 square feet<\/div>\n  <\/div>\n  <div class=\"ex-card\" data-room=\"L-Shape\">\n    <h3>Family room + dining nook<\/h3>\n    <div class=\"ex-step\"><span class=\"ex-arrow\">\u2192<\/span> (18\u00d714) + (8\u00d710) = 252 + 80<\/div>\n    <div class=\"ex-result\">332 square feet<\/div>\n  <\/div>\n<\/div>\n\n<hr class=\"divider\" id=\"reference\">\n\n<h2>Quick Reference Table<\/h2>\n\n<table>\n  <thead>\n    <tr>\n      <th>Shape<\/th>\n      <th>Formula<\/th>\n      <th>Notes<\/th>\n    <\/tr>\n  <\/thead>\n  <tbody>\n    <tr><td>Rectangle<\/td><td>Length \u00d7 Width<\/td><td>Most common room shape<\/td><\/tr>\n    <tr><td>Square<\/td><td>Side\u00b2<\/td><td>Rectangle with equal sides<\/td><\/tr>\n    <tr><td>Triangle<\/td><td>(Base \u00d7 Height) \u00f7 2<\/td><td>Height must be perpendicular to base<\/td><\/tr>\n    <tr><td>Circle<\/td><td>\u03c0 \u00d7 Radius\u00b2<\/td><td>Radius, not diameter<\/td><\/tr>\n    <tr><td>L-Shape<\/td><td>Sum of split rectangles<\/td><td>Divide into 2+ rectangles first<\/td><\/tr>\n    <tr><td>Trapezoid<\/td><td>\u00bd \u00d7 (a + b) \u00d7 h<\/td><td>a, b = parallel sides<\/td><\/tr>\n    <tr><td>Parallelogram<\/td><td>Base \u00d7 Height<\/td><td>Height perpendicular to base<\/td><\/tr>\n    <tr><td>Ellipse<\/td><td>\u03c0 \u00d7 a \u00d7 b<\/td><td>a, b = the two radii<\/td><\/tr>\n  <\/tbody>\n<\/table>\n\n<hr class=\"divider\" id=\"mistakes\">\n\n<h2>Mistakes to Avoid<\/h2>\n\n<div class=\"tips-grid\">\n  <div class=\"tip-card\">\n    <div class=\"tip-icon\">\ud83d\udcd0<\/div>\n    <strong>Measuring triangle height along the slanted side<\/strong>\n    <p>Height must run perpendicular to the base. Using the slanted edge&#8217;s length instead overstates the area.<\/p>\n  <\/div>\n  <div class=\"tip-card\">\n    <div class=\"tip-icon\">\u2b55<\/div>\n    <strong>Using diameter instead of radius for a circle<\/strong>\n    <p>The formula needs the radius \u2014 half the diameter. Squaring the full diameter by mistake inflates the result by roughly four times.<\/p>\n  <\/div>\n  <div class=\"tip-card\">\n    <div class=\"tip-icon\">\ud83d\udd00<\/div>\n    <strong>Trying to force an L-shape into one formula<\/strong>\n    <p>There&#8217;s no single formula for an L-shape \u2014 split it into rectangles first, then add the areas together.<\/p>\n  <\/div>\n  <div class=\"tip-card\">\n    <div class=\"tip-icon\">\ud83e\uddee<\/div>\n    <strong>Forgetting to divide the triangle formula by 2<\/strong>\n    <p>Base \u00d7 height alone gives the area of the rectangle that would enclose the triangle \u2014 the triangle itself is exactly half that.<\/p>\n  <\/div>\n  <div class=\"tip-card\">\n    <div class=\"tip-icon\">\ud83d\udccf<\/div>\n    <strong>Mixing units within one shape&#8217;s measurements<\/strong>\n    <p>All measurements for a single shape&#8217;s formula need to be in the same unit before you calculate \u2014 convert first if any are in inches while others are in feet.<\/p>\n  <\/div>\n  <div class=\"tip-card\">\n    <div class=\"tip-icon\">\ud83d\udd3a<\/div>\n    <strong>Using the wrong two sides for a trapezoid<\/strong>\n    <p>The formula needs the two parallel sides specifically, not just any two sides of the shape \u2014 confirm which sides are actually parallel before measuring.<\/p>\n  <\/div>\n<\/div>\n\n<hr class=\"divider\" id=\"faq\">\n\n<h2>Frequently Asked Questions<\/h2>\n\n<div class=\"faq\">\n  <div class=\"faq-item\">\n    <div class=\"faq-q\">What is the formula for square footage of an irregular shape?<\/div>\n    <p class=\"faq-a\">There&#8217;s no single formula for a fully irregular shape. Split it into simple shapes you do have formulas for \u2014 rectangles, triangles, or trapezoids \u2014 calculate each section&#8217;s area separately, and add them together.<\/p>\n  <\/div>\n  <div class=\"faq-item\">\n    <div class=\"faq-q\">How do you find the square footage of a triangle-shaped room?<\/div>\n    <p class=\"faq-a\">Multiply the base by the height, then divide by 2. The height needs to be measured perpendicular to the base \u2014 straight up from it at a right angle \u2014 not along one of the triangle&#8217;s slanted sides.<\/p>\n  <\/div>\n  <div class=\"faq-item\">\n    <div class=\"faq-q\">How do you calculate the square footage of a circular room?<\/div>\n    <p class=\"faq-a\">Multiply \u03c0 (approximately 3.14159) by the radius squared. If you only have the diameter, divide it by 2 first to get the radius before squaring it.<\/p>\n  <\/div>\n  <div class=\"faq-item\">\n    <div class=\"faq-q\">What&#8217;s the easiest way to measure an L-shaped room?<\/div>\n    <p class=\"faq-a\">Draw a single straight line across the room to split the L into two rectangles. Measure and calculate each rectangle&#8217;s area separately using length \u00d7 width, then add the two totals together for the whole room&#8217;s square footage.<\/p>\n  <\/div>\n  <div class=\"faq-item\">\n    <div class=\"faq-q\">Does the square footage formula change for a home versus a small object?<\/div>\n    <p class=\"faq-a\">No \u2014 the geometry is the same regardless of scale. A triangular tile and a triangular attic gable both use base \u00d7 height \u00f7 2. Only the units and the size of the numbers change.<\/p>\n  <\/div>\n<\/div>\n\n<div class=\"cta-box\">\n  <p>Skip the manual math \u2014 calculate any shape instantly.<\/p>\n  <a href=\"https:\/\/squarefootcalc.com\/\" class=\"cta-btn\">Calculate Square Footage Free \u2192<\/a>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Length times width only gets you through the simplest rooms. The moment a space has a curve, an angle, or an L-shaped floor plan, that one formula stops working \u2014 and you need the right one for the actual shape in front of you. Here&#8217;s every formula you&#8217;re likely to need, in one place. In&#8230;<\/p>\n","protected":false},"author":1,"featured_media":239,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_kad_blocks_custom_css":"","_kad_blocks_head_custom_js":"","_kad_blocks_body_custom_js":"","_kad_blocks_footer_custom_js":"","_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_kad_post_classname":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-245","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog"],"taxonomy_info":{"category":[{"value":1,"label":"Blog"}]},"featured_image_src_large":["https:\/\/squarefootcalc.com\/blog\/wp-content\/uploads\/2026\/07\/Square-Footage-Formula-for-Every-Common-Shape-Rectangle-Triangle-Circle-L-Shape-1024x683.webp",1024,683,true],"author_info":{"display_name":"Luke","author_link":"https:\/\/squarefootcalc.com\/blog\/author\/aziz315\/"},"comment_info":0,"category_info":[{"term_id":1,"name":"Blog","slug":"blog","term_group":0,"term_taxonomy_id":1,"taxonomy":"category","description":"","parent":0,"count":30,"filter":"raw","cat_ID":1,"category_count":30,"category_description":"","cat_name":"Blog","category_nicename":"blog","category_parent":0}],"tag_info":false,"_links":{"self":[{"href":"https:\/\/squarefootcalc.com\/blog\/wp-json\/wp\/v2\/posts\/245","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/squarefootcalc.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/squarefootcalc.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/squarefootcalc.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/squarefootcalc.com\/blog\/wp-json\/wp\/v2\/comments?post=245"}],"version-history":[{"count":1,"href":"https:\/\/squarefootcalc.com\/blog\/wp-json\/wp\/v2\/posts\/245\/revisions"}],"predecessor-version":[{"id":246,"href":"https:\/\/squarefootcalc.com\/blog\/wp-json\/wp\/v2\/posts\/245\/revisions\/246"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/squarefootcalc.com\/blog\/wp-json\/wp\/v2\/media\/239"}],"wp:attachment":[{"href":"https:\/\/squarefootcalc.com\/blog\/wp-json\/wp\/v2\/media?parent=245"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/squarefootcalc.com\/blog\/wp-json\/wp\/v2\/categories?post=245"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/squarefootcalc.com\/blog\/wp-json\/wp\/v2\/tags?post=245"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}