Measuring a room, a floor, or a whole property always starts with one number: the square footage. Our free square footage calculator makes that math effortless — enter your dimensions in feet and inches, add as many rooms or shapes as you need, and get an instant total you can use for flooring, paint, tile, roofing materials, or contractor quotes.
Most online tools only handle one rectangle at a time. Ours goes further: add multiple rooms, triangles for angled walls, and circles for round patios or turrets, then apply a waste factor for cuts and mistakes. Your total also converts to square inches, square yards, and square meters, so the number is ready for any supplier, permit form, or estimate.
Square Footage Calculator
Add rooms and shapes — get your total instantly.
Measuring for a Roofing Project?
Roofing materials are sold by the square (100 sq ft), so an accurate measurement saves you real money on shingles, underlayment, and labor. If you would rather have a pro measure it, Zuniga Roofing offers free on-site roof measurements across the Greater San Diego Area.
How It Works
- Pick a shape — rectangle, triangle, or circle — depending on the area you are measuring.
- Enter the dimensions. Rectangles accept feet and inches; triangles and circles use feet.
- Click "Add Room / Area" to save it to your list, then repeat for every room or section of the project.
- Read your live total at the bottom. Add a 10% waste factor for standard jobs (15% for diagonal layouts), and check the automatic conversions to square inches, square yards, and square meters.
What Affects Your Square Footage Measurement
- Wall-to-wall vs. usable space — closets, stairwells, and fixed cabinets change the number you actually order for.
- L-shaped and angled rooms — split them into rectangles and triangles instead of guessing one big number.
- Rounding — inches add up fast on large projects, so enter them instead of rounding down.
- Waste and cuts — flooring, tile, and roofing all need 10–15% extra for trimming and mistakes.
- Openings — for paint and flooring, pros usually measure the full room and do not subtract small doorways.
Square Footage Formulas
| Shape | Formula | Example |
|---|---|---|
| Rectangle | Length × Width | 12 ft × 10 ft = 120 sq ft |
| Triangle | ½ × Base × Height | 10 ft × 8 ft ÷ 2 = 40 sq ft |
| Circle | π × Radius² | 5 ft radius ≈ 78.5 sq ft |
| L-shaped room | Split into rectangles, then add | Two 10×12 areas = 240 sq ft |
Planning a Roof Replacement in San Diego?
Square footage is only the starting point — pitch, layers, and access all change the final price. Call Zuniga Roofing for a free, exact roof replacement quote with no obligation.
Square Footage Calculator FAQs
Multiply the length by the width in feet. A room that is 15 feet long and 12 feet wide is 180 square feet (15 × 12 = 180). If you measured in inches, divide by 12 to convert to decimal feet first — for example, 6 inches equals 0.5 feet.
Measuring for a roof? Try our roofing calculator for area and squares to convert square footage into roofing squares, or use the roof pitch calculator and roof slope calculator to factor in steepness before ordering materials.
Get Your Free Roofing Estimate Today
Skip the tape-measure math — Zuniga Roofing will measure your roof, explain your options, and give you an honest price. Proudly serving the Greater San Diego Area.