Primer Calculator
Estimates specialized primer gallon requirements based on substrate type: PVA for bare drywall, oil/shellac for water/smoke stain blocking, or multi-surface bonding primer.
Formula
Primer Gallons = (Surface Area × Coats × (1 + Waste %)) ÷ Primer Coverage Rate
1. Total Coated Area = Surface Area × Coats 2. Primer Gallons = (Total Area ÷ Substrate Coverage Rate) × (1 + Waste %) 3. Purchase Gallons = Ceil(Primer Gallons)
Inputs
- Total Surface Area to Prime
- Substrate & Primer Category
- Primer Coats
Worked example
Sealing 500 sq ft of newly taped and sanded drywall with 1 coat of PVA drywall sealer.
Outcome: 500 sq ft divided by 300 sq ft/gal equals 1.67 gallons. With 10% waste (1.83 gallons total), purchase two 1-gallon cans or one 5-gallon pail for larger jobs.
Why is PVA primer necessary for new drywall?
Bare drywall paper and joint compound absorb liquid at drastically different rates. PVA primer seals both substrates equally so topcoat paint dries to a uniform sheen without blotchy flashing.