Interior paint calculator (simple)

How to use (3 steps)

Pick Metric or US units, coats, coverage, and waste allowance.
Use Room mode for length, width, height, doors/windows, and ceiling; use Area mode to type a known surface.
Check the live results, set can size if needed, then copy the URL.

A sample room is prefilled so you see results instantly.

Unit system

Metric (m, m², L)

US customary (ft, ft², gal)

Number of coats

Coverage per unit m²/L

Typical interior wall paints cover around 8–12 m² per L.

Waste / extra allowance (%)

Paint can size (optional) L

Room length m

Room width m

Ceiling height m

Doors

Windows

Include ceiling

Door and window areas are subtracted automatically.

Area, paint, and cans refresh as you edit.

Per coat area

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All coats total

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Coverage used

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Theoretical paint

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With extra allowance

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Paint can size (optional)

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If your openings or walls differ a lot from this simple model, increase the extra allowance or treat tricky areas as a separate run.

What if my doors or windows are a different size?

This tool subtracts a standard door and window size. If yours differ a lot, adjust the counts or switch to the area mode with your measured surface.

How should I plan for multiple colors or finishes?

This calculator estimates a single paint. Split the area by color/finish, run the calculation for each, and round up cans separately.