Free tool · for homeowners, contractors and real estate
Square Footage Calculator: Feet, Inches and Any Shape
Add every room or area, in feet and inches or metric, subtract islands and closets, and get the total in square feet, square yards and square meters, with waste, cost and boxes of flooring.
Square Footage Calculator
- Area 1120 sq ft
Measure each wall at floor level and round up to the next inch. 1 sq yd = 9 sq ft; 1 m² = 10.764 sq ft; 1 acre = 43,560 sq ft.
Square Footage Formulas for Every Shape
Measure in feet (or convert inches by dividing by 12), then use the formula for the shape.
| Shape | Formula | Example |
|---|---|---|
| Rectangle or square | Length × width | 12 × 10 = 120 sq ft |
| Triangle | Base × height ÷ 2 | 10 × 6 ÷ 2 = 30 sq ft |
| Circle | 3.1416 × radius × radius | 10 ft across: 3.1416 × 5 × 5 = 78.5 sq ft |
| Trapezoid | (Top + bottom) ÷ 2 × height | (8 + 12) ÷ 2 × 5 = 50 sq ft |
| L-shaped room | Split into two rectangles and add | (20 × 10) + (8 × 8) = 264 sq ft |
| Border or ring | Outer circle − inner circle | 12 ft and 8 ft across: 113.1 − 50.3 = 62.8 sq ft |
How to Measure a Room in 5 Steps
- Sketch the floor on paper and split it into simple shapes.
- Measure wall to wall at floor level, ignoring baseboards, and round up to the next inch.
- Write feet and inches for each side, for example 12 ft 6 in.
- Add closets and alcoves as their own areas if the flooring goes into them.
- Subtract anything the flooring won’t cover, such as a kitchen island or fireplace hearth.
Square Footage of a House
For mortgages, appraisers measure gross living area under the ANSI Z765 standard, which Fannie Mae has required since April 1, 2022. It counts finished, above-grade space only. Garages, porches, unfinished areas and any space partly or fully below grade are listed separately (National Association of Realtors).
So a home listed by its total floor area can show a smaller number on the appraisal. Measure the outside walls of each finished level and add them.
Room Size to Square Feet Chart
Common room sizes in the US, with the area and how much flooring to buy with 10% extra.
| Room size | Square feet | Square yards | With 10% extra | Typical use |
|---|---|---|---|---|
| 10 × 10 ft | 100 sq ft | 11.1 | 111 sq ft | Small bedroom or office |
| 10 × 12 ft | 120 sq ft | 13.3 | 132 sq ft | Bedroom |
| 12 × 12 ft | 144 sq ft | 16.0 | 159 sq ft | Bedroom |
| 12 × 14 ft | 168 sq ft | 18.7 | 185 sq ft | Primary bedroom |
| 12 × 16 ft | 192 sq ft | 21.3 | 212 sq ft | Living room |
| 14 × 16 ft | 224 sq ft | 24.9 | 247 sq ft | Living room |
| 14 × 20 ft | 280 sq ft | 31.1 | 308 sq ft | Family room |
| 15 × 20 ft | 300 sq ft | 33.3 | 330 sq ft | Great room |
| 12 × 20 ft | 240 sq ft | 26.7 | 264 sq ft | One-car garage |
| 20 × 20 ft | 400 sq ft | 44.4 | 441 sq ft | Two-car garage |
| 24 × 24 ft | 576 sq ft | 64.0 | 634 sq ft | Large two-car garage |
| 5 × 8 ft | 40 sq ft | 4.4 | 44 sq ft | Full bathroom |
Square Feet Conversions
| 1 square yard | 9 square feet |
|---|---|
| 1 square meter | 10.764 square feet |
| 1 acre | 43,560 square feet |
| 1 square foot | 144 square inches |
| 100 square feet | 1 “square” of roofing |
How Much Extra to Buy
- About 10% for laminate, vinyl plank or hardwood laid straight.
- 15% or more for diagonal or herringbone layouts, small rooms with many cuts, or tile.
- Round up to full boxes, and keep one spare box for future repairs.
- Buy one lot. Color can vary between production batches.
These are common rules of thumb; the flooring maker’s installation guide comes first.
Add This Calculator to Your Website, Free
Flooring stores, remodelers, painters and contractors: let customers measure their project on your site, in your colors, with a button to request your estimate.
Paste it into any page of your website as an “HTML” or “embed” block. It’s free, needs no account and collects no visitor data.
Questions
How do I calculate square footage?
Multiply the length by the width in feet. A room 12 feet long and 10 feet wide is 12 × 10 = 120 square feet. For an L-shaped or odd room, split it into rectangles, work out each one, and add them together.
How do I calculate square footage with inches?
Turn the inches into a decimal of a foot first by dividing by 12. 12 feet 6 inches is 12.5 feet, so a room 12 ft 6 in by 10 ft is 12.5 × 10 = 125 square feet. The calculator does this for you in Feet + inches mode.
How many square feet is a 12x12 room?
144 square feet. A 10x12 room is 120 square feet and a 12x14 room is 168 square feet.
How much extra flooring should I buy?
A common rule is about 10% extra for straight-laid flooring and 15% or more for diagonal, herringbone or patterned layouts, small rooms with many cuts, or tile that may break. Check the manufacturer’s guidance and buy from one lot so colors match.
How do I convert square feet to square yards?
Divide by 9, because one square yard is 3 ft × 3 ft. 270 square feet is 30 square yards. Carpet is often priced per square yard.
How many square feet are in an acre?
An acre is 43,560 square feet, which is about 4,047 square meters.
Do garages and basements count in a home’s square footage?
Not under the ANSI Z765 standard that Fannie Mae requires appraisers to use. Gross living area is finished, above-grade space; garages, porches, unfinished areas and any space partly or fully below grade, such as a walk-out basement, are listed separately.
How do I find the square footage of a circle?
Square the radius (half the diameter) and multiply by 3.1416. A round patio 10 feet across has a radius of 5 feet: 5 × 5 × 3.1416 = about 78.5 square feet.