Paint Primer Calculator
Gallons of primer for walls or ceilings.
Enter your values
Enter the surface area in sq ft.
Enter the coverage per gallon in sq ft.
Choose one of: Painted drywall, New drywall / masonry.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Primer needed
- 2.7 gal
- Effective coverage used
- 300 sq ft/gal
- Quarts (if under 1 gal)
- 10.7 qt
Quick answer
Primer need is the surface area divided by the coverage per gallon, usually a single coat.
gallons = area / coverage per gallon
At a glance
| What it does | Gallons of primer for walls or ceilings. |
|---|---|
| Category | Home & DIY |
| Inputs needed | Surface area, Coverage per gallon, Surface type |
| Main output | Primer needed |
| Formula | gallons = area / coverage per gallon |
| Cost | Free — no sign-up, no download |
How to use the Paint Primer Calculator
- 1Measure the total surface area to prime.
- 2Enter the coverage rate from the primer can.
- 3Select porous surfaces like new drywall or masonry to automatically reduce coverage.
Inputs explained
- Surface area(sq ft)
- Enter the surface area in sq ft.
- Coverage per gallon(sq ft)
- Enter the coverage per gallon in sq ft.
- Surface type
- Choose one of: Painted drywall, New drywall / masonry.
Worked example
Using the values the calculator loads with:
Inputs
- Surface area800 sq ft
- Coverage per gallon300 sq ft
- Surface typePainted drywall
Results
- Primer needed2.7 gal
- Effective coverage used300 sq ft/gal
- Quarts (if under 1 gal)10.7 qt
Frequently asked questions
Do porous surfaces need more primer?
Yes, new drywall, stucco and masonry soak up more primer, cutting effective coverage by roughly 25%.
Do I need two coats of primer?
Usually one coat is enough unless covering a very dark colour or a stain.
What do I need to enter into the Paint Primer Calculator?
Just 3 values: surface area, coverage per gallon, surface type. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Paint Primer Calculator work out the answer?
Primer need is the surface area divided by the coverage per gallon, usually a single coat. It applies the formula gallons = area / coverage per gallon and shows the working so you can check each step by hand.
Is the Paint Primer Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.