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PaintingPrimer Calculator — How Much Primer Do I Need?
Add up your wall length, enter the height and coats, and get the gallons of primer. Primer covers a bit less than paint, especially on bare or patched surfaces.
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How this calculator works
We figure wall area (length × height), multiply by coats, and divide by about 300 sq ft per gallon — typical primer coverage. Bare drywall, wood, and patched areas drink more.
What changes how much you need
- One coat of primer is normal; bare or stained surfaces may want two.
- A tinted primer (toward your topcoat color) can save you a finish coat.
- Self-priming paint can skip separate primer on previously painted, sound walls.
- Primer covers less than paint on porous surfaces — plan ~250–300 sq ft/gal.
Frequently asked questions
How much does a gallon of primer cover?
About 250–300 sq ft per coat — less than finish paint, since primer often goes on bare, thirsty surfaces.
Do I need primer?
Prime bare drywall/wood/masonry, big color changes, stains, and patched areas. Sound, previously painted walls in a similar color often don’t need it.
Should I tint the primer?
Yes, toward your topcoat color when making a big change — it can turn three finish coats into two.