Measurement · free tool
Square Footage Calculator
Find the square footage of any room or lot. Add as many areas and shapes as you need — get sq ft, sq yd, sq m and acres, plus the material you'll need.
Square Footage Calculator
Area of any room or lot — add as many shapes as you need.
1 Your areas
2 Total area
| Area | Shape | Sq ft |
|---|
Estimates only — measure carefully and split odd rooms into simple shapes. See how we calculate · Updated monthly
Method · how it works
How to calculate square footage
Square footage is just area in feet: length times width. For anything more complex, break it into simple shapes and add them up.
Measure in feet
Measure length × width. If you measured in inches, divide by 12 to get feet first.
Use the shape's formula
Circle is π r², triangle is ½ b h, trapezoid is ½(a+b) h.
Split odd rooms
Divide an L, T or U shape into rectangles (and triangles), and measure each part.
Add up & convert
Add the areas. Then ÷9 for sq yd, ÷43,560 for acres, or price it per sq ft.
An L-shaped room
Bump-out: 4 × 6 = 24 sq ft
168 + 24 = 192 sq ft
two rectangles, added
Sources: standard geometry (area formulas) · ANSI Z765 / Fannie Mae measuring guidelines
Formulas verified against standard references · Updated monthly
Estimates only — measure twice, and for flooring or paint add a waste margin on top of the area. The calculator lets you stack as many shapes as your space needs.
Formulas · by shape
Square footage formulas
Convert every measurement to feet first, then use the formula for the shape. Each is built into the calculator above.
12 × 16 = 192 sq ft
Most rooms12 × 12 = 144 sq ft
Equal sides10 ft across = 78.5 sq ft
Roundbase 10, height 8 = 40 sq ft
Corners10 & 14, height 8 = 96 sq ft
Angled walls12×16 − 10×14 = 52 sq ft
WalkwaysOdd room? Split it into these shapes, work out each, and add them together — or just stack areas in the calculator.
Irregular spaces
How to measure an odd-shaped room
L-shapes, T-shapes, bay windows, alcoves — any space breaks down into simple shapes you can measure and add together.
Break it into rectangles
Draw the room on paper and split it into the largest rectangles you can. Fewer, bigger sections mean fewer measurements and fewer mistakes.
Add triangles & circles
Handle the leftover corners with a triangle (½ b h) and curved bays with a circle or half-circle. Work out each piece on its own.
Add them up (subtract cut-outs)
Sum every piece for the total. Subtract anything you won't cover — islands, cabinets, a fireplace hearth — using the border/frame option.
In the calculator, each piece is just another area — add a row per section, pick its shape, and the total updates as you go. No paper math required.
Units · conversion
Converting square feet
Once you have the area in square feet, switching to yards, meters or acres is simple — the calculator shows all of them at once.
1 unit equals
| Unit | In square feet |
|---|---|
| 1 square yard | 9 sq ft |
| 1 square meter | 10.764 sq ft |
| 1 acre | 43,560 sq ft |
| 1 hectare | 107,639 sq ft |
| 1 square foot | 144 sq in |
Square feet to acres
Divide by 43,560
Price per sq ft: divide the total price by the total square feet — or enter a rate in the calculator's Convert & cost tab to price a whole project.
Real estate
Square footage of a house
Measuring a home for sale or appraisal is stricter than a flooring estimate. Only finished, livable space counts toward gross living area (GLA).
Finished rooms with walls, floor and ceiling, and heating or cooling — bedrooms, living areas, hallways and finished closets all count toward GLA.
Garages, unfinished basements and attics, open porches and balconies are excluded — even if large. Below-grade space is usually reported separately.
GLA drives a home's market value, appraisal and property taxes — so measurements follow the ANSI Z765 standard that lenders and appraisers rely on.
For a home sale, follow the ANSI Z765-2021 method (adopted in Fannie Mae's measuring guidelines). For a flooring, tile or paint project, measure the actual surface you're covering instead — and add a waste margin.
Answers
Square footage FAQs
How do I calculate square footage?
Measure length and width in feet and multiply them. A 12 by 16 ft room is 192 sq ft. For other shapes, use the matching formula and add the parts.
How many square feet is a 12x12 room?
A 12 ft by 12 ft room is 144 square feet — just 12 multiplied by 12.
How do I find the square footage of an irregular room?
Split it into rectangles, triangles and circles, work out each area, and add them together. In the calculator, add one area row per section.
How do I convert square feet to acres?
Divide by 43,560 — one acre is 43,560 sq ft. So 10,000 sq ft is about 0.23 acre, and a quarter acre is 10,890 sq ft.
How do I calculate price per square foot?
Divide the total price by the total square feet. A $200,000, 2,000 sq ft home is $100 per sq ft. To price a project, multiply area by the rate.
Does a garage count toward a home's square footage?
No. Only finished, heated living space counts toward gross living area — garages, unfinished basements and open porches are excluded.
What is the difference between square feet and linear feet?
Linear feet measure length only (one dimension); square feet measure area (length x width). Trim is bought by linear foot, flooring by square foot.