How much paint do you need?

Measure the room, subtract the openings, and get a practical shopping list for walls, ceilings, coats, and a little breathing room.

Your room

Room dimensions

Inside measurements

Openings to subtract

Use zero if none

Coverage plan

Adjust to match the label

What are you painting?

The calculation

(wall perimeter × height − doors − windows + ceiling) × coats × (1 + waste) ÷ coverage

A standard door is estimated at 21 ft² (1.95 m²), and a standard window at 15 ft² (1.39 m²). For unusually large openings, reduce the final result manually or count only typical openings.

Before you buy

  1. Use the coverage printed on your exact paint can; texture, porosity, and colour changes can lower it.
  2. Keep wall and ceiling paint separate if the colour or finish differs—calculate each as its own job.
  3. For several rooms, run each room separately and add only paints with the same colour and finish.

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