Square Footage Calculator
Measure length and width in feet to get the area in square feet. Add a price per square foot to estimate material cost, or multiple areas for several rooms.
Area = length × width. For materials like flooring or sod, add 5–10% extra for waste and cuts.
How to use this calculator
Enter the length and width of the space in feet. The square footage appears immediately. If you have measurements in inches, divide by 12 before entering (for example, 144 inches = 12 feet). If you are calculating multiple identical rooms or spaces — like three bedrooms of the same size — set the number of areas and the total updates automatically.
To estimate material cost, enter an optional price per square foot. This works for hardwood flooring, laminate, carpet, tile, sod, paint, and any material priced per square foot. The result is a material estimate; add waste factor (see below) and labor separately.
How square footage works
Square footage is a measure of area — the amount of two-dimensional surface a shape covers. For a rectangle, it is simply length multiplied by width. The result is expressed in square feet (ft²) as long as both input dimensions are in feet. There is nothing more to the core formula; the challenge is usually in measuring accurately and handling rooms that aren't a simple rectangle.
For rooms with alcoves, closets, bay windows, or L-shapes, the standard approach is to divide the space into rectangles, calculate each one separately, and sum the results. Subtract fixed obstacles like kitchen islands or built-in cabinets if you're calculating how much flooring to order and those areas won't be covered.
Worked example — flooring for a living room
Your living room measures 16 ft × 13 ft and you're installing hardwood flooring at $4.75 per square foot.
- Area: 16 × 13 = 208 ft²
- Material cost: 208 × $4.75 = $988.00
- With 10% waste: 208 × 1.10 = 229 ft² to order
- Adjusted cost: 229 × $4.75 = $1,087.75
The waste-adjusted figure is what you bring to the flooring supplier. This accounts for cuts at the walls, the occasional damaged board, and the starting course that often requires trimming.
Measuring L-shaped and irregular rooms
Most rooms that seem complicated can be decomposed into two or three rectangles. For an L-shaped room, extend one wall mentally to create a large rectangle, then subtract the missing corner piece. Or split the L into two rectangles that together fill the space without overlap. Either approach gives the same answer.
For a triangular section (common in attic rooms, bay additions, or angled walls), the area is ½ × base × height. A bay window bump-out of approximately triangular shape — base 6 ft, depth 3 ft — adds about ½ × 6 × 3 = 9 ft² to the room total.
How to interpret your result
The square footage is the net area of the measured space. When buying materials, always buy more than the net area to account for waste. The right waste percentage depends on the material and layout:
- Straight-lay tile or planks: 5–8% extra
- Diagonal tile pattern: 10–15% extra (more cuts at every wall)
- Carpet: 5–10% extra, sometimes more for awkward room shapes
- Sod or artificial turf: 5–10% extra for trimming
- Paint: Plan for a second coat; a gallon covers roughly 350–400 ft² per coat
Common mistakes to avoid
- Measuring in inches but entering as feet: If your tape reads 144 and you mean 144 inches (12 feet), entering 144 into the calculator gives you 144 feet — an area 12× too large. Always confirm you're entering feet, or convert first (divide inches by 12).
- Forgetting closets and alcoves: If you're calculating flooring for a bedroom, include the closet floor area. It's easy to measure only the main room and then wonder why the flooring comes up short.
- Not accounting for waste: Ordering the exact measured square footage almost always leads to running short. Even in a perfectly rectangular room, you lose material at the starting row and the cut pieces at the end wall.
- Confusing square feet with linear feet: A 12-foot-wide roll of carpet sold by the linear foot is not the same as square footage. Multiply linear feet by the roll width to get square footage for carpet priced this way.
- Mixing square feet and square yards: Some flooring is still priced per square yard. Divide your square footage by 9 to convert, or the calculator does it for you.
The formula
Area (ft²) = Length (ft) × Width (ft) × Number of areas
Square yards = Square feet ÷ 9 · Material cost = Area × Price per ft² · Order quantity = Area × (1 + waste %)
How we calculate this
Area is calculated as Length (ft) × Width (ft) × Number of areas. If a price per square foot is entered, the cost estimate is Area × Price. Square yards are shown as Area ÷ 9. All values are computed at full floating-point precision and rounded for display.
Frequently asked questions
How do you calculate square footage?
Multiply length by width, both in feet. A room 14 ft long and 11 ft wide is 14 × 11 = 154 square feet. If you have measurements in inches, divide each dimension by 12 first to convert to feet before multiplying.
How do I find the square footage of an L‑shaped or irregular room?
Divide the space into simple rectangles, calculate each section separately, and add the results. For example, an L-shaped room can be split into two rectangles. For triangular sections, the area is ½ × base × height. Add everything together for the total.
How many square feet are in a square yard?
One square yard equals 9 square feet (because 3 ft × 3 ft = 9 ft²). To convert square feet to square yards, divide by 9. Carpet and some flooring materials are still priced and sold by the square yard, so this conversion is useful when shopping.
How much extra flooring or tile should I buy?
Add 5–10% above your measured square footage to cover cuts, waste, and pattern matching. For tile with a diagonal pattern, add 15%. For irregularly shaped rooms, the waste factor can be higher because more cuts are needed at the edges.
How do I measure a room in feet if I only have a tape measure in inches?
Measure in inches, then divide by 12 to get feet (or keep it as a decimal: 136 inches ÷ 12 = 11.33 feet). Enter the decimal value into the calculator. Alternatively, measure in feet and inches and convert the inches portion: 11 ft 4 in = 11 + (4 ÷ 12) = 11.33 ft.
How do I calculate the square footage of a house?
Measure each room or area separately (length × width), then add all the areas together. Finished areas count toward livable square footage; garages, unfinished basements, and covered porches typically do not, depending on local appraisal conventions. Use this tool for each room and sum the totals.
How do I convert square feet to square meters?
Multiply square feet by 0.0929 to get square meters. Alternatively, divide by 10.764. For example, 500 square feet × 0.0929 ≈ 46.5 square meters. This is useful when comparing home sizes listed in different measurement systems.
How do I estimate how much paint I need from the square footage?
A standard gallon of interior paint covers approximately 350–400 square feet with one coat. Calculate the total wall area (perimeter × wall height, minus doors and windows), then divide by 350–400 for gallons needed. Buy an extra 10% for a second coat or touch-ups.