Primer Calculator — Surface Prep Quantities
Estimate primer quantity based on model surface area and application method.
How We Calculate This
Primer needed (ml) = surface area (cm²) × usage rate (ml/cm²) × coats. The usage rate depends on application method: estimates assume thin scale-model coats, with rates of roughly 0.02 ml/cm² for spray cans, 0.018 ml/cm² for brush-on, and 0.015 ml/cm² for airbrush. Spray cans use the most because a 400 ml aerosol is only ~30% paint (the rest is solvent and propellant) and 20-50% is lost to overspray, whereas an airbrush atomises thinned paint with little waste. These are starting assumptions — adjust them in Advanced Options to match your own primer and technique. One thin coat is usually sufficient.
Frequently Asked Questions
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Last updated: February 2026
All calculations are estimates. Always verify quantities before purchasing materials.