Square Footage Calculator
This square footage calculator adds up the area of rectangles, triangles, circles and trapezoids and converts the total to acres, square yards and square metres. Square feet = length × width in feet, and acres = square feet ÷ 43,560.
At a glance
- What it does: adds any number of areas in feet, inches, yards or metres, with waste and an optional price per sq ft.
- Acres converter: square feet, acres, square metres and hectares, both ways.
- What it costs: nothing. It runs in your browser, and nothing you type is sent or stored.
Area calculator for rooms, yards and lots
Add one line for each part of the space. Split odd shapes into rectangles, triangles and circles, then add them up.
Square feet to acreage conversion calculator
Type in any box and the others update. One acre is exactly 43,560 sq ft.
acres = square feet ÷ 43,560
square feet = acres × 43,560
| Square feet | Acres | Square metres |
|---|---|---|
| 1,000 sq ft | 0.0230 | 92.9 |
| 2,000 sq ft | 0.0459 | 185.8 |
| 5,000 sq ft | 0.1148 | 464.5 |
| 7,500 sq ft | 0.1722 | 696.8 |
| 10,000 sq ft | 0.2296 | 929.0 |
| 15,000 sq ft | 0.3444 | 1,393.5 |
| 20,000 sq ft | 0.4591 | 1,858.1 |
| 21,780 sq ft | 0.5000 | 2,023.4 |
| 43,560 sq ft | 1.0000 | 4,046.9 |
| 87,120 sq ft | 2.0000 | 8,093.7 |
| 100,000 sq ft | 2.2957 | 9,290.3 |
| 217,800 sq ft | 5.0000 | 20,234.3 |
| Acres | Square feet | Square metres |
|---|---|---|
| 0.1 acres | 4,356 | 405 |
| 0.25 acres | 10,890 | 1,012 |
| 0.5 acres | 21,780 | 2,023 |
| 0.75 acres | 32,670 | 3,035 |
| 1 acre | 43,560 | 4,047 |
| 2 acres | 87,120 | 8,094 |
| 5 acres | 217,800 | 20,234 |
| 10 acres | 435,600 | 40,469 |
How to calculate square footage
Measure in feet and multiply. For other shapes, use the matching formula:
rectangle = length × width
triangle = base × height ÷ 2
circle = π × (diameter ÷ 2)²
trapezoid = (side a + side b) ÷ 2 × height
If you measured in inches, divide square inches by 144. In yards, multiply square yards by 9. In metres, multiply square metres by 10.7639.
Worked example: a room and a lot
- A 12 ft × 15 ft room: 12 × 15 = 180 sq ft, or 20 sq yd (180 ÷ 9).
- With 10% extra for flooring cuts: 180 × 1.10 = 198 sq ft to order.
- A 100 ft × 150 ft lot: 100 × 150 = 15,000 sq ft; 15,000 ÷ 43,560 = 0.344 acres.
The calculator opens with the room and the converter with the lot, so you can check both.
Odd-shaped rooms and yards
Draw the space and cut it into simple shapes. An L-shaped room is two rectangles. A bay window is a rectangle plus a trapezoid. A curved bed is close to half a circle, so add a circle line and halve it, or enter the diameter of a circle of the same area. Add each piece as its own line.
Square footage for flooring, painting and landscaping quotes
- Flooring and tile: measure the floor wall to wall, add extra for cuts, and divide by the coverage on each box.
- Painting: wall area is the room’s perimeter times the wall height, less large doors and windows. Divide by the coverage on the paint can and multiply by the number of coats.
- Sod, seed and mulch: measure the lawn or beds in square feet. For mulch or soil, multiply by depth in feet for cubic feet, and divide by 27 for cubic yards.
- Cleaning and pressure washing: many companies quote by the square foot, so a quick total helps you price on the first call.
From measurement to a quote
Multiply the area by your rate, then check the margin with the margin calculator. Bill the job with the free invoice generator, or email invoices with a card payment link through BrickByClick Free for $0 a month. Starter, $99 a month, adds estimates customers accept online, a job tracker and a calendar.
Sources
- 1 acre = 43,560 sq ft (10 square chains); 1 ft = 0.3048 m exactly, so 1 sq ft = 0.09290304 m²; 1 acre = 4,046.8564224 m²: NIST Handbook 44, Appendix C (General Tables of Units of Measurement). Since 2023 the US uses the international foot for these conversions (NIST, U.S. survey foot).
- Area formulas for rectangles, triangles, circles and trapezoids are standard geometry.
Questions people ask
How do I calculate square footage?
How many square feet are in an acre?
How do I convert square feet to acres?
How many square feet is half an acre?
How do I convert square feet to square yards?
How do I convert square feet to square metres?
How do I find the square footage of an irregular room?
How much extra flooring should I buy?
How do I calculate the square footage of walls for painting?
How many square feet is a hectare?
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