Square footage calculator

Frequently asked questions

Which unit system should I pick?

Use whichever matches the unit your material is sold in. Flooring, drywall, and paint in the US are priced per square foot, so imperial (ft → sq ft) is the natural fit. Most of the rest of the world prices by the square metre, so metric (m → sq m) is the right pick there. The underlying math (length × width plus optional waste) is identical either way — the calculator just reports the result in the unit you selected.

How much waste allowance should I add for flooring?

A common starting point is 10% for straightforward rectangular rooms with straight-lay patterns. Diagonal or herringbone patterns, rooms with many cuts around obstacles, or materials prone to breakage often call for 15–20%. Check the manufacturer or installer recommendation for the specific product.

Does this calculator handle non-rectangular rooms?

It models a single rectangle. For L-shaped or irregular rooms, break the space into separate rectangles, calculate each one, and add the results together before applying the waste allowance.

What is the difference between base area and total area with waste?

Base area is the raw floor space: length times width. Total area adds the waste factor on top of that, representing how much material to actually purchase so cuts and unusable pieces do not leave you short.

Does the waste allowance cover grout lines or subfloor gaps?

No — the estimate is based purely on the face area of the material. Grout joints, underlayment, and installation tolerances vary by product and are typically addressed in the installer's specifications rather than in a simple area calculation.