Square Footage Calculator
Square footage is the area of a space measured in square feet. To calculate it, multiply length × width (both in feet). For example, a 12 ft × 15 ft room is 180 square feet. Divide by 9 to convert square feet to square yards.
Enter the length and width in feet, get the area in square feet (and square yards) with every step shown.
How to calculate square footage
Type the length and width of your room, yard, or project area in feet, then press Calculate. The calculator multiplies them to give the area in square feet, then converts to square yards, the unit flooring and carpet installers quote in, with each step on screen so you can check the arithmetic or show your working.
Both inputs must be positive numbers. Decimals are fine (a room that is 12.5 ft by 10.25 ft works exactly as you would expect), and the calculator accepts values like 1/2 as well.
Square footage formula
Square footage is just the area of a rectangle: length × width. Measure the two longest perpendicular sides of the space with a tape measure, keeping both in the same unit (feet). Multiply them. That is the whole method, the reason it trips people up is never the multiplication, it is measuring in mixed units (one side in feet, the other in inches) or forgetting that an L-shaped room must be split into rectangles first.
For the square-yard conversion, divide square feet by 9: a square yard is 3 ft × 3 ft, so it contains nine square feet. The calculator shows this division explicitly.
Square footage calculation example
Example: a 12 ft × 15 ft bedroom
Step 1, Formula: Area = length × width.
Step 2, Substitute: 12 ft × 15 ft.
Step 3, Calculate: 12 × 15 = 180 square feet.
Step 4, Square yards: 180 ÷ 9 = 20 sq yd.
Sanity check: a 10 × 10 room is 100 sq ft, so 180 for a slightly larger bedroom is in the right neighborhood. Flooring installers usually add 5–10% extra for cuts and waste, for this room, order about 190–200 sq ft of material.
More examples: 10 × 12 ft = 120 sq ft (13.33 sq yd); 25 × 40 ft = 1000 sq ft; 14.5 × 9.75 ft = 141.4 sq ft.
Common mistakes
- Mixing feet and inches: a room measured as 12 ft by 146 in is not 12 × 146, convert 146 in to 12.17 ft first, or convert everything to inches and divide by 144 at the end.
- Measuring an L-shape as one rectangle: split irregular rooms into rectangles, compute each area, and add. One bounding rectangle over-counts the missing corner.
- Forgetting the waste factor: the calculator gives the exact area; real projects need 5–10% extra for cuts, pattern matching, and mistakes.
- Confusing square feet with feet: “12 square feet” is an area (about 3 × 4 ft), not a 12-foot length. The unit matters when ordering materials.
When to use it
Square footage runs an enormous share of everyday math: flooring, carpet, and tile quotes; paint coverage (divide wall square footage by the paint’s coverage per gallon); sod and mulch for yards; real-estate listings; and HVAC sizing, where systems are specified per square foot of conditioned space. Whenever a price is quoted “per square foot,” this is the number being priced.
If your project also needs volume, soil, concrete, or gravel, continue to the cubic yard calculator or the gravel calculator.
Full walkthrough: measuring a real room
Grab a tape measure and record the longest wall: say 14 ft 6 in. Convert the inches: 6 ÷ 12 = 0.5, so 14.5 ft. Measure the adjacent wall: 11 ft 3 in → 11.25 ft. Enter 14.5 and 11.25 above: 14.5 × 11.25 = 163.125 sq ft, which is 18.125 sq yd. For laminate flooring at 10% waste: 163.125 × 1.10 ≈ 180 sq ft to order. The step panel shows the multiplication broken out, so you can verify against a hand calculation.
Frequently asked questions
Measure the length and width in feet and multiply them: area = length × width. A 12 ft by 15 ft room is 180 square feet. For irregular shapes, split them into rectangles, compute each, and add.
Nine. A square yard is 3 ft × 3 ft = 9 sq ft, so divide square feet by 9. The 180 sq ft bedroom above is 20 square yards, the unit carpet is usually priced in.
Divide it into two (or more) rectangles along a natural seam. Calculate each rectangle’s square footage separately with the calculator, then add the results together.
Yes, order 5–10% more than the exact square footage for cutting waste, pattern matching, and future repairs. For 180 sq ft, that means ordering roughly 190–200 sq ft.
Convert inches to feet first (divide by 12), then multiply length × width. Or multiply in inches and divide by 144 (square inches per square foot). A 144 in × 180 in room is 25920 ÷ 144 = 180 sq ft.
100 square feet (10 × 10). In square yards that is 100 ÷ 9 ≈ 11.1 sq yd. Add 5–10% for waste when ordering flooring: about 105–110 sq ft.