Build CalculatorsSquare Footage Calculator
Calculate the area of a room, floor, yard or lot. Combine rectangles, circles, triangles and trapezoids, subtract the parts you don't need, and price flooring, paint or sod by the square foot.
Area
Same area in other units
- Square yards
- 13.33
- Square meters
- 11.15
- Square inches
- 17,280
- Acres
- 0.0028
How to measure for square footage
- Sketch the space and split it into simple shapes. Most rooms are one rectangle; L-shaped rooms are two.
- Measure each shape wall to wall at floor level. Round up to the next inch rather than down.
- Enter each shape as its own area. Use Subtract an area for things you will not cover — an island, a hearth, a patio inside a lawn.
- Add a waste percentage if you are buying material that gets cut, then enter the price per square foot to get the total.
Area formulas
- Rectangle or square: length × width.
- Circle: π × (diameter ÷ 2)². A 10 ft round patio is 3.1416 × 25 = 78.5 sq ft.
- Triangle: base × height ÷ 2, where the height is measured at a right angle to the base.
- Trapezoid: (side a + side b) ÷ 2 × height, for shapes with two parallel sides, such as a lot that narrows toward the back.
Every dimension can have its own unit. The calculator converts all of them to feet before multiplying, so 12 ft × 150 in gives the same result as 12 ft × 12.5 ft.
Worked examples
Main area 12 × 14 ft = 168 sq ft, plus a 6 × 8 ft dining alcove = 48 sq ft: 216 sq ft. With 10% waste you buy 237.6 sq ft; at $3.50 per sq ft the flooring costs about $832. That is 24 sq yd if the carpet store quotes by the yard.
A 100 × 150 ft lot is 15,000 sq ft. Subtract a 30 × 40 ft house footprint (1,200 sq ft) and the lawn is 13,800 sq ft, or 0.32 acres. Lawn products are often priced per 1,000 sq ft, so that is 13.8 units of seed or fertilizer.
Square footage of common room sizes
| Room | Sq ft | Sq yd | m² |
|---|---|---|---|
| 10 × 10 ft | 100 | 11.1 | 9.3 |
| 10 × 12 ft | 120 | 13.3 | 11.1 |
| 11 × 12 ft | 132 | 14.7 | 12.3 |
| 12 × 12 ft | 144 | 16 | 13.4 |
| 12 × 14 ft | 168 | 18.7 | 15.6 |
| 12 × 16 ft | 192 | 21.3 | 17.8 |
| 14 × 16 ft | 224 | 24.9 | 20.8 |
| 16 × 20 ft | 320 | 35.6 | 29.7 |
| 20 × 20 ft | 400 | 44.4 | 37.2 |
| 24 × 24 ft | 576 | 64 | 53.5 |
Area unit conversions
| Unit | Square feet | Other units |
|---|---|---|
| 1 square foot | 1 | 144 sq in · 0.111 sq yd · 0.0929 m² |
| 1 square yard | 9 | 1,296 sq in · 0.836 m² |
| 1 square meter | 10.764 | 1.196 sq yd |
| 1 acre | 43,560 | 4,840 sq yd · 4,046.9 m² · 0.405 ha |
From square feet to materials
Once you know the area, the amount of loose material depends only on depth. One cubic yard of any material covers:
| Project | Depth | Notes |
|---|---|---|
| 1 inch deep | 324 sq ft | Compost topdressing on a lawn. |
| 2 inches deep | 162 sq ft | Topdressing, walkway gravel. |
| 3 inches deep | 108 sq ft | Typical mulch depth. |
| 4 inches deep | 81 sq ft | Typical concrete slab and gravel base depth. |
| 6 inches deep | 54 sq ft | Driveway slab or base. |
Take your total to the mulch calculator or the gravel calculator and enter it with the Known area shape. For concrete, enter the slab's length and width in the concrete slab calculator.
Related calculators
- Concrete CalculatorCubic yards and 40, 60 or 80 lb bags for slabs, footings, columns and steps.
- Concrete Slab CalculatorSlab concrete, bag count, rebar grid and gravel base for patios and driveways.
- Gravel CalculatorCubic yards and tons of gravel, crushed stone or road base for any area.
- Mulch CalculatorHow many bags or yards of mulch for beds, rings around trees and playgrounds.
Frequently asked questions
How do I calculate square footage?
Measure the length and width in feet and multiply them. A room 12 ft long and 14 ft wide is 12 × 14 = 168 square feet. If a measurement includes inches, convert it to decimal feet first: 12 ft 6 in is 12.5 ft.
How do I find the square footage of an L-shaped or irregular room?
Split the floor into rectangles (and triangles or half-circles where needed), calculate each piece, and add them. An L-shaped room made of a 12 × 14 ft area and a 6 × 8 ft alcove is 168 + 48 = 216 sq ft. To leave out something like a kitchen island or fireplace hearth, subtract its area.
How do I convert square inches to square feet?
Divide by 144, because one square foot is 12 × 12 = 144 square inches. If you measured in inches, multiply length × width in inches and divide by 144: a 30 × 60 in shower base is 1,800 ÷ 144 = 12.5 sq ft.
How many square feet are in an acre?
One acre is 43,560 square feet, which is 4,840 square yards or about 4,047 square meters. A square acre is about 208.7 ft on each side. A typical quarter-acre suburban lot is 10,890 sq ft.
How much extra flooring should I buy?
Add 5–10% to the measured square footage for cuts and waste with a straight lay. Use 10–15% for diagonal or herringbone patterns, large-format tile, and rooms with many corners. Buy it all from one production lot so color matches.
What counts toward the square footage of a house?
In the US, listed living area usually follows the ANSI Z765 standard: finished, heated space above grade, measured to the outside of exterior walls. Garages, unfinished basements, porches and open-to-below areas are not included, which is why a listing figure is often smaller than a room-by-room total that includes them.