Primer Calculator

How to Use This Calculator

1. 1Enter total square footage of walls and ceilings to be primed.
2. 2Select the surface type to get the correct coverage rate.
3. 3Click Calculate Materials for gallons and can count.

About This Material

Primer is a preparatory coating applied before the topcoat paint to ensure proper adhesion, uniform sheen, and consistent color. Different surface types require different primer formulations. PVA (polyvinyl acetate) primer is the standard choice for new, unpainted drywall — it seals the porous gypsum surface so the topcoat does not absorb unevenly, which causes a blotchy appearance called flashing. PVA primer costs $12 to $18 per gallon and covers approximately 300 square feet per gallon on new drywall. For previously painted surfaces in good condition, a bonding primer or a paint-and-primer-in-one product is sufficient, covering up to 400 square feet per gallon. Bare wood surfaces require an oil-based or shellac-based primer to seal the grain and prevent tannin bleed-through, especially on knotty pine, cedar, and redwood — coverage is lower at around 250 square feet per gallon due to wood's absorbency. Stain-blocking primer (shellac-based like Zinsser BIN or oil-based like Kilz Original) is essential for covering water stains, smoke damage, crayon marks, and ink — these specialty primers have the lowest coverage at approximately 200 square feet per gallon but provide unmatched stain sealing. Popular primer brands include Kilz (Masterchem), Zinsser (Rust-Oleum), and Sherwin-Williams PrepRite. For best results, tint your primer close to the final topcoat color — most paint stores can add a small amount of colorant to white primer at no extra charge.

Installation Tips

• •Apply primer with the same roller nap you plan to use for the topcoat.
• •Allow primer to dry completely before topcoating — typically 1 to 2 hours for latex, 24 hours for oil-based.
• •Tint the primer to match or approximate the topcoat color for better hide in fewer coats.
• •Use a brush to cut in corners and edges, then roll the field areas.

Common Mistakes to Avoid

• ⚠Skipping primer on new drywall — causes flashing (uneven sheen) that is visible in certain lighting angles.
• ⚠Using latex primer on stains — water-based primers cannot block tannin, nicotine, or water stains; use shellac or oil-based.
• ⚠Applying primer too thick — heavy coats take longer to dry and may peel; one even coat is sufficient.
• ⚠Priming over dust and debris — always wipe or vacuum surfaces before priming for proper adhesion.

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