How Much Primer Do I Need?

When you need primer, how to calculate how much, and typical primer coverage for drywall, wood and stained surfaces.

Primer seals the surface, helps paint stick and stops stains or dark colors showing through. It also usually covers less area than paint, so it's easy to under-buy.

Here's when you need it and how much to get.

When you need primer

• New drywall or fresh patches.
• Bare wood, metal or masonry.
• Water stains, smoke or marker that would bleed through.
• Big color changes, especially light over dark (a tinted primer helps).
• Glossy surfaces you're painting over.

How much primer

Primer = area ÷ coverage. Usually one coat is enough. Primer typically covers 200–300 sq ft per gallon, with the lower end for porous surfaces like new drywall and bare wood.

Example: a 12×12 room has about 350 sq ft of walls, which works out to about 1.2–1.75 gallons of primer. Buy 2 gallons, or one gallon if you're only spot-priming patches.

Use the paint calculator with 1 coat and 250 coverage to get a primer estimate.

Paint-and-primer in one?

Self-priming paints work well on previously painted, sound surfaces. For new drywall, stains or bare wood, a dedicated primer still does a better job.