Free SqFt Calculator for Any Shape
Calculate square footage for rooms, flooring projects, land, and construction. Supports seven shapes, five input units, waste factor and cost estimator. Everything runs in your browser — no sign-up, no upload.
Last updated:Tip: If you only have the diameter, divide by 2 to get the radius.
L-shape = two rectangles sharing a corner.
Add one row per rectangle and we'll sum them.
Specialized Square Footage Calculators
Pick the calculator that matches your project for the most accurate results and scenario-specific guidance.
Main Calculator
All seven shapes with waste factor, cost, and visualization.
Room Calculator
Dedicated tool for bedrooms, kitchens, and living rooms.
House Calculator
Whole-home total following the ANSI Z765 standard.
Flooring Calculator
Hardwood, vinyl, and laminate with 10% waste factor.
Tile Calculator
Tile counts and box quantities with pattern waste.
Carpet Calculator
Square yards from sq ft with padding included.
Paint Calculator
Gallons per wall at 350 sq ft coverage.
Roof Calculator
Shingle squares and pitched-roof adjustments.
Cost per Sq Ft
Two-way converter for budgeting renovations.
How to Calculate Square Footage in Three Steps
- Pick the right shape for your space. Most rooms are rectangles; rooms with alcoves are L-shapes or irregular; round patios and pools are circles.
- Measure in any unit. Enter feet, inches, yards, meters, or centimeters. The calculator converts everything to feet before computing the area.
- Read the result in square feet — plus instant conversions to square meters, square yards, and acres.
Need more detail? Our full how-to-calculate-square-feet guide walks through each shape with worked examples and illustrated diagrams.
Square Footage Formulas: Quick Reference
| Shape | Formula | Example |
|---|---|---|
| Rectangle | L × W | 12 × 10 = 120 sq ft |
| Square | S × S | 10 × 10 = 100 sq ft |
| Circle | π × r² | π × 6² ≈ 113.1 sq ft |
| Triangle | (B × H) / 2 | (14 × 9) / 2 = 63 sq ft |
| Trapezoid | ((a + b) / 2) × H | ((8+14)/2) × 6 = 66 sq ft |
| L-Shape | (L1·W1) + (L2·W2) | (16·8)+(8·6) = 176 sq ft |
See our complete square feet formula reference with derivations.
How Many Square Feet Is My Room?
Check the most searched room dimensions. Every size links to a dedicated page with unit conversions, typical uses, and related tools.
10 × 10 = 100 sq ft
Small bedroom, home office.
10×1210 × 12 = 120 sq ft
Standard bedroom.
12×1212 × 12 = 144 sq ft
Dining or guest room.
12×1512 × 15 = 180 sq ft
Small master bedroom.
14×1614 × 16 = 224 sq ft
Mid-size living room.
15×2015 × 20 = 300 sq ft
Large living room.
16×2016 × 20 = 320 sq ft
Large master suite.
20×2020 × 20 = 400 sq ft
Great room, two-car garage.
AllBrowse all sizes
See 60+ room dimensions with notes.
Unit Conversions at a Glance
| From | To | Formula |
|---|---|---|
| sq ft | sq m | × 0.092903 (tool) |
| sq ft | sq yd | ÷ 9 (tool) |
| sq ft | acres | ÷ 43,560 (tool) |
| sq m | sq ft | × 10.7639 (tool) |
| acres | sq ft | × 43,560 (tool) |
| sq ft | sq in | × 144 (tool) |
Why Trust This SqFt Calculator
- Formulas verified against the ANSI Z765 home measurement standard and the US National Institute of Standards and Technology (NIST) conversion factors.
- No data leaves your browser. Every calculation is pure JavaScript running locally.
- Mobile-first. All inputs are at least 48×48 px and the result updates instantly as you type.
- Accessible. Full keyboard navigation, ARIA labels, and WCAG AA color contrast.
Frequently Asked Questions
How do I calculate square footage?
For a rectangular room, multiply length × width in feet. A 12 ft × 10 ft room is 120 sq ft. For other shapes, pick the matching tab in the calculator above — circle, triangle, trapezoid, L-shape, and irregular rooms all use their own geometry formulas.
What is a square foot?
A square foot (sq ft or ft²) is the area of a square with 1-foot (12-inch) sides. One square foot equals 144 square inches, 0.0929 square meters, or about 0.1111 square yards.
Is this sqft calculator free?
Yes. Every calculator on this site is free, requires no sign-up, and has no ads inside the tool itself. Your measurements never leave your device because all math runs in your browser.
What shapes can I calculate?
Rectangle, square, circle, triangle, trapezoid, L-shape, and fully irregular rooms built from any number of rectangles. The same tool also supports multi-room totals when you need whole-home square footage.
How accurate is the result?
The calculator uses exact geometry formulas and IEEE-754 double-precision math. The only source of error is your own measurements — typical tape-measure error is roughly ±0.5 inch, so expect practical accuracy within ±1%.
Does it work offline?
Once the page loads, yes — the calculator runs entirely client-side. You can even save the page with browser File → Save, then open the HTML file offline and keep using it.
Can I use inches, meters, or centimeters?
Yes. Each dimension input has a unit selector (ft, in, yd, m, cm). The calculator converts every input to feet before multiplying, so you can mix units across fields if needed.
What if my room has an alcove or cut-out?
Switch to L-shape if the room has one rectangular bump, or Irregular if it has several. You can add as many sub-rectangles as you need; the total updates instantly.