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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
Priming is strongly recommended. It provides a uniform surface for paint to grip, reveals surface defects, and ensures consistent colour. Skip primer only on pre-coloured snap kits that will not be painted.
Grey is the most versatile. White primer is best under light or bright colours. Black primer works well with dark colour schemes and creates natural shadows if coverage is slightly uneven. Some modellers use specific colours like red-brown under tank green.
Apply primer in thin, even coats. You should still be able to see panel lines and fine detail after priming. If detail disappears, the primer is too thick. One thin coat is usually sufficient.
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Last updated: February 2026
All calculations are estimates. Always verify quantities before purchasing materials.