How the result is calculated
- 01
Length in feet = feet + inches / 12 - 02
Area in square feet = converted length x converted width - 03
Area in square yards = square feet / 9
MEASUREMENT
Square Footage Calculator
Calculate the square footage of a room from feet and inches, with square yards included. Enter your measurements below and the estimate updates instantly.
Formula, validation and worked example reviewed November 12, 2026. See our calculation methodology.
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MEASUREMENT
US UNITSSquare Footage
YOUR ESTIMATE
240 sq ft26.7 sq yd20 ft × 12 ft · Geometric area before waste
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Formula and example
Square footage without unit mistakes.
To calculate square footage of a room, convert every inch measurement to feet before multiplying. This feet-and-inches calculator keeps the conversion precise and shows both square feet and square yards.
How do you calculate square footage from feet and inches?
Tape measures read in feet and inches, but area formulas require decimal feet. Divide any inch measurement by 12 before multiplying length by width, then divide square feet by 9 when ordering carpet or turf sold by the square yard:
Areasq ft=(Lft + Lin12) · (Wft + Win12)
(Decimal feet area)Areasq yd=Areasq ft9
(Square yards)where:
- L_ft, W_ft – Whole feet measured along the room or slab length and width;
- L_in, W_in – Extra inches converted to decimal feet (6 in = 0.50 ft, 3 in = 0.25 ft); and
- Area_sq ft – Net surface area in square feet. Convert area into 4×8 panels with the plywood sheet calculator or slab yardage with the concrete calculator.
12 ft 6 in by 10 ft 3 in room
- 12 ft 6 in becomes 12.5 ft.
- 10 ft 3 in becomes 10.25 ft.
- 12.5 x 10.25 = 128.125 sq ft.
Quick reference chart
Common Room Sizes: Square Feet, Square Yards & 10% Waste Allowance
1 square yard = 9 square feet. Add 10% for standard straight-lay flooring or drywall cuts.
| Room Size (ft) | Net Area (sq ft) | Square Yards (sq yd) | With 10% Waste (sq ft) |
|---|---|---|---|
| 10 × 10 ft | 100.0 sq ft | 11.1 sq yd | 110.0 sq ft |
| 10 × 12 ft | 120.0 sq ft | 13.3 sq yd | 132.0 sq ft |
| 12 × 15 ft | 180.0 sq ft | 20.0 sq yd | 198.0 sq ft |
| 12 × 20 ft | 240.0 sq ft | 26.7 sq yd | 264.0 sq ft |
| 20 × 20 ft | 400.0 sq ft | 44.4 sq yd | 440.0 sq ft |
| 24 × 24 ft | 576.0 sq ft | 64.0 sq yd | 633.6 sq ft |
Common mistakes to avoid
- Entering 6 inches as 0.6 feet. Six inches is 0.5 feet.
- Measuring an irregular room as one rectangle instead of adding smaller rectangles.
- Rounding each dimension before the final calculation.
- Treating exact floor area as the final material order without allowing for cuts or layout.
Questions answered
Calculator FAQ
How do I calculate square footage of a room?+
Measure the room's length and width, convert any extra inches to feet, then multiply the two converted dimensions. Split irregular rooms into rectangles and add their areas.
How do I calculate square footage for flooring with waste?+
Calculate room length times width in feet to get base square footage, then multiply by 1.10 for a standard 10% waste factor (or 1.15 for diagonal tile). For example, a 12x15 ft room is 180 sq ft; with 10% waste, order 198 sq ft of flooring.
How does the calculator handle inches?+
It divides inches by 12, adds that value to the feet field, and then multiplies the converted dimensions.
How do I measure an L-shaped room?+
Split it into two rectangles, calculate each area separately, and add the two square-foot results.
How many square feet are in one square yard?+
One square yard equals 9 square feet, so divide square feet by 9.
Does the result include material waste?+
No. The result is geometric area only. Add an allowance appropriate to the material, pattern, cuts, and project conditions.
Can I use this for walls or ceilings?+
Yes for one rectangular surface. Calculate each wall or ceiling section separately and add the results.
Practical selection guide
Square footage calculations for flooring, tile and paint.
Convert dimensions accurately, split complex spaces, and add the appropriate 10% waste factor for straight-lay material orders.
Flooring square footage (+10% waste)
For hardwood, tile, laminate, or carpet, always order 10% extra for straight runs and 15% for diagonal or herringbone patterns to absorb cutting waste and room contours.
L-shaped & multi-room layouts
Break non-rectangular rooms into smaller rectangles (A and B), multiply length × width for each section, and sum them up before adding waste.
Square feet to square yards
Carpet and turf are often priced per square yard. Divide your net square footage by 9 to get square yards (e.g. 180 sq ft ÷ 9 = 20 sq yd).
Wall & ceiling paint area
Multiply perimeter by ceiling height to get total wall area, then subtract 21 sq ft for standard interior doors and 15 sq ft per window.