Paint Coverage Calculator — How Much Paint Do I Need?

Wall area minus openings, times coats, divided by real coverage (≈10 m²/L emulsion) — with a 10% wastage allowance baked in.

Part of our paint coverage guide — per-surface coverage tables for walls, floors, fences and masonry.

Quick answer: Enter room dimensions, doors and windows, and coats — get the exact paint litres (and US gallons) you need using real coverage rates. Free, instant, private; stops you over-buying tins.

–Litres needed

–US gallons

–Net wall area

How to use

Enter room length, width and ceiling height.
Count doors and windows (or adjust the defaults).
Set coats and your paint's coverage (printed on the tin); read litres + gallons instantly.

About this tool

Paint tins state coverage per litre (typically 10–13 m²/L for wall emulsion, less for rough surfaces). The tool computes net wall area from perimeter × height minus doors (≈1.9 m² each) and windows (≈1.5 m² each), multiplies by coats, divides by your tin's coverage and adds 10% cutting/patching allowance — the same math professional decorators use for estimates.

FAQ

What coverage should I use?

Check the tin: most emulsions are 10–13 m²/L. Textured or dark walls: use 8 and add a coat.

Should I paint the ceiling too?

Add its area (length × width) as an extra surface if using the same product — or use our area converter for odd shapes.

Why 10% extra?

Cutting-in, roller splash and touch-ups always consume more than flat-area math suggests.

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The complete paint coverage calculator guide

Prefer the long version — a worked example, the mistakes people actually make, and answers to real questions? The blog guide Paint Coverage Calculator — Complete Guide, Mistakes & FAQ covers all of it step by step.

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Related: wallpaper room preview tool

Tool	Paint Coverage Calculator — How Much Paint Do I Need?
Category	Home Decor
Price	Free — no payment, no account
Data & privacy	Runs in your browser; inputs are not stored on our servers
Last updated	2026-10-09

Paint Coverage Calculator — How Much Paint Do I Need?

How to use

About this tool

FAQ

Rate this tool

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The complete paint coverage calculator guide

Key Facts

Sources & Further Reading