Primer Calculator
Calculate primer needed for bare drywall, stains, color changes, or new construction using area and coverage rate.
Formula & Explanation
Primer is a base coat used to seal surfaces, hide stains, and improve topcoat adhesion. It typically has lower coverage than topcoat paint. Formula: Gallons = (Surface area × Primer coats) ÷ Primer coverage per gallon Example: 280 sqft × 1 primer coat ÷ 300 sqft/gal = 0.93 gallons → purchase 1 gallon can Cost comparison: Primer ($35/gal) vs. using extra topcoat ($50/gal). Using primer saves money when needed for stain blocking or color changes.
Assumptions
- •Primer coverage: 250-350 sqft/gallon (varies by type and brand; check product specifications)
- •Interior latex primer typically covers 300-350 sqft/gallon
- •Oil-based primer typically covers 250-300 sqft/gallon
- •Shellac-based stain blocker covers 200-300 sqft/gallon
- •One primer coat is typical; two coats for severe stains or dark-to-light color changes
- •Primer is required on bare drywall, bare wood, stains, and water damage
- •Primer is optional when repainting with similar color over existing paint in good condition
- •Primer costs approximately 20-30% less than topcoat paint
Example Calculation
280 square feet with one primer coat at 300 sqft/gallon coverage requires 0.93 gallons, round up to 1 gallon can. Primer saves approximately $9.33 compared to using topcoat instead.
Inputs
Results
Primer Types and Coverage
| type | coverage | use | cost |
|---|---|---|---|
| Latex interior primer | 300-350 sqft/gal | Bare drywall, light stains | $20-$40/gal |
| Oil-based primer | 250-300 sqft/gal | Bare wood, glossy surfaces | $30-$50/gal |
| Shellac stain blocker | 200-300 sqft/gal | Heavy stains, water damage | $25-$45/gal |
| Bonding primer (e.g., Zinsser Bulls Eye) | 250-400 sqft/gal | Glossy surfaces, tile | $30-$50/gal |
| Rust-blocking primer | 250-300 sqft/gal | Metal, rust spots | $25-$45/gal |
Frequently Asked Questions
Related Calculators
Paint Calculator
Estimate paint required for a room by perimeter, height, doors, windows, number of coats, and paint coverage rate.
Interior Paint Calculator
Calculate interior paint needed by specifying wall area, number of coats, and paint coverage rate for smooth drywall.
Wall Paint Calculator
Calculate paint needed for a single wall by specifying width, height, coats, and coverage rate.
Paint Cost Calculator
Calculate total paint project cost by combining paint material, labor, waste, and tax.
Paint Coverage Calculator
Calculate how far your paint will go by entering gallons available, coverage rate, and number of coats.