Construction & Home · Area & Materials
Formula verified
Square Footage Calculator
Enter a room's length and width in feet and inches, and this works out the square footage, along with square yards, acres and square meters, plus a total cost if you enter a price per square foot.
Room
ft
in
ft
in
$
On-screen number pad
Tap to type into the highlighted field
Square footage
125.00
sq ft
Square yards
13.89
Square meters
11.61
Step-by-step proofCheck by hand
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How square footage is calculated
Length and width are each converted from feet-and-inches to a single decimal-feet figure (inches ÷ 12), then multiplied together to get the area in square feet. From there, dividing by 9 gives square yards, dividing by 43,560 gives acres, and multiplying by 0.092903 gives square meters.
The formula
square feet = (length ft + length in ÷ 12) × (width ft + width in ÷ 12)
Worked example
A room measuring 12 ft 6 in by 10 ft is 12.5 × 10 = 125.00 square feet — about 13.89 square yards, or 11.61 square meters.
Frequently asked questions
Why does this ask for feet and inches separately instead of one decimal number?
Room measurements are usually read off a tape measure in feet and inches (12 ft 6 in), not as a decimal (12.5 ft) — entering it the way it was measured avoids a manual conversion and the rounding mistakes that come with it.
Why show square yards and acres as well as square footage?
Flooring, carpet and turf are commonly priced and sold by the square yard, while land and larger lots are measured in acres — showing all three, plus square meters for materials sourced with metric measurements, means you don't need a separate converter.
Does the cost estimate include waste or cutting allowance?
No — the total cost shown is simply square footage times the price you enter, with no allowance for waste, offcuts or pattern matching. Most flooring and material suppliers recommend adding 5–10% extra to the exact square footage to cover cutting waste; add that to the price you enter, or to the total, yourself.
Sources and method
- Area conversion factors (square feet to square yards, acres, square meters) — general published mathematics and standard unit-conversion tables.