Almost every home project starts with the same question: how big is the area? Flooring, tile, paint, mulch, and sod are all sold or estimated by the square foot, so one accurate area measurement feeds every material decision that follows. This calculator works out the square footage of a single rectangular room, several rooms added together, or an L-shaped space with a missing corner.
Enter your measurements in feet and inches as decimal feet (for example, 10 ft 6 in is 10.5 ft). The tool handles the three room shapes that cover the vast majority of real homes, so you can measure a space once and reuse the result across the rest of your project.
Square Footage Calculator
Worked example: three room shapes
Single rectangle. A living room measures 12 ft by 15 ft. Area = 12 × 15 = 180 sq ft. That single number is what you would hand to a flooring or tile estimate.
Multiple rooms. A bedroom is 12 × 10 ft (120 sq ft) and the adjoining bathroom is 10 × 8 ft (80 sq ft). Added together: 120 + 80 = 200 sq ft. Measuring room by room and summing is more accurate than trying to measure an irregular whole at once.
L-shape. A kitchen-diner fits inside a 20 × 14 ft rectangle (280 sq ft), but an 8 × 6 ft corner is taken up by a stairwell (48 sq ft). Area = 280 − 48 = 232 sq ft. The alternative — splitting the L into two rectangles and adding them — gives exactly the same answer.
How the calculation works
The math is basic geometry, and there is nowhere for a fudge factor to hide:
- Rectangle: Area = length × width
- Multiple rooms: add the area of each rectangle
- L-shape: outer rectangle − missing corner, or split the shape into two rectangles and add
All measurements must be in the same unit before you multiply. To convert inches into decimal feet, divide by 12: 3 in = 0.25 ft, 6 in = 0.5 ft, 9 in = 0.75 ft. Our full methodology, including how every calculator on this site is tested against hand-worked answers, is on the How We Calculate page.
Typical material costs per square foot
Once you know the area, these are the material price ranges it will be multiplied against. Typical US prices, checked November 2026. Materials only; prices vary by region and store.
| Material | Typical cost per sq ft |
|---|---|
| Luxury vinyl plank (LVP) | $2.00 – $5.00 |
| Laminate flooring | $1.50 – $3.50 |
| Ceramic floor tile | $1.50 – $5.00 |
| Carpet | $2.00 – $5.00 |
| Solid hardwood | $4.00 – $10.00 |
Remember that the material calculators add a waste allowance on top of your area, so the purchase quantity will be higher than the bare square footage. That is deliberate — running short mid-project costs more than one extra box.
Measuring checklist
- Sketch the space on paper and split anything irregular into rectangles before you measure.
- Measure each wall twice; in older homes, opposite walls are often different lengths. Use the larger figure.
- Write measurements as feet and decimal inches (10 ft 6 in → 10.5 ft) so the multiplication stays clean.
- Include closets and alcoves in floor area; leave out nothing the material will actually cover.
- Measure in the room itself, not from a floor plan — plans and reality often differ by a few percent.
FAQ
How do I calculate the square footage of a room?
Multiply the length by the width, both in feet. A 12 × 15 ft room is 180 sq ft. For rooms that are not rectangles, split them into rectangles, calculate each, and add the results.
How do I convert inches to feet for the calculator?
Divide the inches by 12. So a wall that is 10 ft 6 in long is 10.5 ft, and 8 ft 3 in is 8.25 ft. Enter the decimal value.
Should I subtract closets or doorways from floor area?
Include closets — flooring and tile run into them. Doorways sit within the rectangles you already measured, and the openings themselves are too small to change a material order, so there is no need to subtract them.
Does square footage include the walls?
No. Square footage on this page is floor (or ground) area. Walls are a different measurement: for a rectangular room, wall area is the perimeter multiplied by the ceiling height, which is what the Paint Calculator uses.
How accurate does my measurement need to be?
Within an inch or two is fine for material estimating. Every material adds a waste allowance on top of the area, which absorbs small measuring errors — but measure twice anyway, because a one-foot mistake is not absorbed.
Related calculators
With your area in hand, the Flooring Calculator turns it into boxes of LVP, laminate, or hardwood, and the Tile Calculator works out tiles and boxes for floors and walls. For walls, the Paint Calculator converts wall area into gallons, and outdoors the Mulch Calculator turns bed area and depth into bags or cubic yards.
Estimates only: results are based on standard formulas and the measurements you enter, and actual material needs vary with site conditions and product dimensions. Confirm your measurements and the manufacturer’s specifications before buying. These tools do not cover structural, load-bearing, electrical, gas, or plumbing design — for safety-critical work, hire a licensed professional.