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Home & DIY calculator

Square Footage Calculator

Enter two dimensions and get the usable area before you order material.

Part of: Flooring & tiling · Epoxy floors & resin casting

Your measurements

Metric + imperial

How this calculator works

Area = length × width for each rectangle, added together. Purchase area = total area × (1 + waste percentage ÷ 100).

Worked example

A 12 ft × 10 ft room has 120 ft². With 10% waste, plan for 132 ft². An L-shaped room of 12 ft × 10 ft plus 6 ft × 4 ft is 144 ft², or 158.4 ft² with 10% waste.

Assumptions to check

  • Each area is a rectangle; split other shapes into rectangles.
  • Waste is applied to the full base area.
  • Irregular cutouts should be measured separately and added or subtracted.

Read the calculation and QA methodology →

Common questions

FAQ

How much waste should I add?

Straight layouts often start near 5–10%. Complex patterns, diagonal cuts, or many corners can require more. Use the value recommended for your material and project.

Can I calculate several rooms?

Yes. Enter the first room, then up to two more rectangles in the optional fields; the calculator adds them. For more rooms, or rooms with different waste rates, calculate them separately and add the results.

How do I calculate the square footage of a house?

Measure each room or section as a rectangle, multiply length by width, and add the results. Example: rooms of 12 x 10 ft, 14 x 12 ft and 10 x 9 ft are 120 + 168 + 90 = 378 sq ft. Listing or appraisal square footage follows its own rules (for example, which walls and floors count), so use this for material estimates.

How many square feet is 10 x 15?

A 10 ft by 15 ft area is 150 square feet (about 13.94 m²). With a 10% waste allowance, plan for 165 square feet of material.

Does the calculator round up?

Area results show decimals. Product packaging should be rounded up using the flooring or tile calculator.