Why are primer and topcoat calculated separately?
Primer and topcoat often have different coverage rates and coat counts, so each is estimated on its own and rounded up to whole gallons independently.
Paint Calculator
Estimate primer and topcoat gallons.
You'll need — gal of paint to cover — sq ft.
Area source
Use the active Room Layout's wall area or override manually. This page paints wall area only, not the ceiling.
Chained wall area
Run Room Layout first to prefill paint with the active project's wall area.
Paint inputs
Coverage per gallon and coat count stay editable; 0 or negative coats are treated as no topcoat.
Raw drywall porosity
A fresh, unprimed drywall surface absorbs the first coat that touches it (the primer if one is used, otherwise the topcoat) and needs extra volume.
You'll need — gal of paint to cover — sq ft.
You'll need
Paint results
Warnings
- ERROR Enter the area being painted -- without it there is nothing to count.
Detail values
- Total gallons
- —
Assumptions
- Primer coverage: 300 sq ft/gal
- Topcoat coverage: 350 sq ft/gal
- First coat on raw drywall: No
Included: topcoat paint, primer.
Not included: labor, delivery, permits, disposal of waste material, ceiling paint.
Material List
About this calculator
Enter area, coats, and coverage per gallon to get separate primer and topcoat purchase quantities.
FAQ
Can I skip the primer coat?
Yes. Set primer coats to zero and only the topcoat gallons will be estimated.
Does coverage per gallon change by product?
Yes. Coverage per gallon is editable so you can match the specific product label instead of a generic default.
What is the raw drywall porosity option?
A fresh, unprimed drywall surface absorbs whichever coat touches it first (the primer if one is used, otherwise the topcoat), needing extra volume. Turn this on to apply an editable porosity allowance -- 25% by default -- to that first coat only.
Disclaimer
Material estimate only; verify actual product coverage on the label before purchasing.