Construction

Subfloor Area Calculator

Calculate subfloor area with a waste allowance and an approximate sheet count.

Floor length (m)
Floor width (m)
Waste allowance (%)

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This result shows the floor area, the larger area to cover once the waste allowance is added, and how many standard sheets to order.

Formula

Floor area = length multiplied by width. Area with waste = area multiplied by (1 + waste as a decimal). Sheet count = waste area divided by 2.88 square metres per standard sheet, rounded up.

How it works

Measure the floor's length and width, then add a waste percentage for cuts around edges and obstacles. Dividing by a standard sheet size gives a sheet count for ordering. Rooms with many corners or angles need a higher waste allowance.

Worked example

For example, a floor 5 m long and 4 m wide has an area of 20.00 sq m; with a 10% waste allowance the area to cover is 22.00 sq m, which needs 8 standard sheets at 2.88 sq m each.

FAQs

Why 2.88 square metres per sheet?
That is the area of a common 2400 by 1200 millimetre sheet. If your sheets differ, adjust the count accordingly.

How much waste is normal?
Ten percent suits simple rectangles; complex rooms may need fifteen percent or more.

Does this include adhesive and fixings?
No, those are ordered separately based on the sheet count and manufacturer guidance.

Rough estimate only — consult a licensed professional for structural work before building.