What Is a Square Footage Calculator?
A square footage calculator finds the area of a room, wall, lot, or surface in square feet. Square footage is the foundation of countless home and construction decisions — how much flooring, carpet, tile, paint, sod, or drywall to buy, and how to estimate project cost. Enter the length and width of a space and the calculator returns the area instantly, and it can total multiple rooms and apply a price per square foot for a quick cost estimate.
How to Use the Square Footage Calculator
- Enter length — the longer dimension of the space, in feet.
- Enter width — the shorter dimension, in feet.
- Calculate — the area in square feet is shown immediately.
- Optional: add a price per square foot to estimate material or project cost, and add multiple areas for a running total.
How to Calculate Square Footage
For a rectangle or square, the formula is simply:
Square Footage = Length (ft) × Width (ft)
A room 12 ft by 10 ft is 120 square feet. If measurements are in inches, divide by 12 to convert to feet first, or measure in feet and inches and convert the inches to a decimal (6 inches = 0.5 ft).
Area Formulas for Other Shapes
| Shape | Formula |
|---|---|
| Rectangle / Square | Length × Width |
| Triangle | ½ × Base × Height |
| Circle | π × Radius² |
| L-shaped room | Split into rectangles, add areas |
Common Uses for Square Footage
- Flooring: buy enough carpet, hardwood, laminate, or tile, plus 5%–10% extra for waste and cuts.
- Paint: wall area divided by coverage per gallon tells you how many gallons you need.
- Real estate: total living area is a key metric for pricing and comparison.
- Landscaping: sod, mulch, and gravel are sold by area or volume derived from square footage.
Measuring Tips for Accuracy
Measure at floor level, take readings in feet and inches, and convert inches to decimals before multiplying. For irregular or L-shaped rooms, divide the space into rectangles, calculate each separately, and add them together. Always add a waste allowance — typically 10% — for flooring and tile to cover offcuts and mistakes.
Frequently Asked Questions
How do you calculate square footage?
Multiply length by width when both are in feet. A 15 ft by 12 ft room is 180 square feet. For inches, convert to feet first by dividing by 12.
How do I find the square footage of an L-shaped room?
Divide the L-shape into two rectangles, calculate the square footage of each, and add them together for the total area.
How much extra flooring should I buy?
Add 5%–10% to your square footage to allow for cutting waste, pattern matching, and future repairs. For diagonal or herringbone patterns, lean toward 10%–15%.
How do I convert square inches to square feet?
Divide the area in square inches by 144, since one square foot contains 144 square inches.
Is this square footage calculator free?
Yes — it is completely free, with no signup, and works for rooms, walls, and lots of any size.