calcs.homes
calcs.homes
Enter your room, lot, or slab dimensions and we'll work out the square footage — a rectangle sq ft calculator, circle area calculator, and triangle area calculator in one.
Estimate only — measure twice before ordering materials.
For a rectangle we multiply length by width. For a circle we use area = π × (diameter ÷ 2)², squaring the radius rather than the diameter. For a triangle we multiply base × height and divide by two. Once we have square footage (or square meters), we also convert to square yards by dividing by 9, and to acres by dividing by 43,560 — the number of square feet in an acre.
These are the standard geometric area formulas for each shape, not simplified approximations — using diameter directly instead of radius, or skipping the ÷2 for a triangle, are among the most common measuring mistakes people make by hand. Converting automatically to square yards and acres saves you from re-deriving those factors yourself when ordering flooring, sod, or comparing lot sizes.
Measure the length and width of the room in feet, then multiply them together. For an L-shaped room, split it into two rectangles, calculate each separately, and add the results.
Measure the diameter (the distance straight across the widest point), select "Circle" above, and enter it — we handle the πr² formula for you.
Yes — switch the toggle at the top of the page to "EU · m / cm" and enter your measurements in meters to get square meters.
One acre is 43,560 square feet. The result panel above shows acres automatically once you've entered your dimensions.