What this calculator works out
This calculator estimates the paint a model needs from its length and a complexity factor, and converts that into pots at your pot size.
It is a rough guide. Modelling paint is bought in small quantities and the real constraint is usually having the right colour rather than enough of it.
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Before you buy paint
- Model length is a proxy for surface area, which is what paint actually covers. It works within a subject type and poorly across them — a 25 cm ship and a 25 cm aircraft have very different areas.
- The complexity factor covers multiple coats, camouflage schemes and colour changes.
- Airbrushing uses considerably more paint than brushing, because much of it is lost as overspray.
- Primer, gloss coats and varnish are separate and are not included.
A pot of a standard colour can be replaced. A custom mix, matched by eye across several pots, generally cannot — and a model half-painted in a shade you can no longer reproduce is a genuine problem. Mixing more than needed and storing the remainder in a labelled sealed jar costs pennies and removes the risk.
How this calculator works
Length times a rate and a complexity factor:
Millilitres = length in cm × 0.6 × complexity factor, minimum 5 ml
Pots = millilitres ÷ pot size, rounded up
Simple 0.8 · Average 1.0 · Detailed or multiple coats 1.4The 5 ml floor reflects that even a very small model needs a workable quantity in the pot — you cannot brush from less than a few millilitres regardless of what the arithmetic says.
Worked example: a 25 cm model
Using the default figures — a 25 cm model, simple scheme, 17 ml pots:
- Estimated paint: 12 ml
- Pots: 1
One pot covers it, which is the usual answer for a single colour on a model this size. The complexity factor matters more for schemes than for size: a detailed multi-coat finish on the same model needs 21 ml — two pots — and a four-colour camouflage scheme needs a pot of each regardless of how little of each is used. Colour count drives the shopping list far more than volume does.
Common mistakes
- Buying by volume rather than by colour. The scheme's colour count is what determines the order.
- Not allowing for airbrush overspray. It uses substantially more than brushing.
- Mixing a custom shade without making extra. It cannot be matched later.
- Forgetting primer and varnish. They are separate products and separate quantities.
- Comparing length across subject types. A ship and an aircraft of the same length differ hugely in area.
Frequently asked questions
Acrylic or enamel?
Acrylics dominate modern modelling — lower odour, water cleanup, and good airbrush performance. Enamels give a harder finish, level better by brush and are preferred by some for washes and weathering. Both work; the practical differences are ventilation, cleanup and drying time rather than results.
How much paint does an airbrush use?
Considerably more than a brush — much of the paint is lost as overspray, and the cup needs enough volume to work with. Thinning also multiplies the volume sprayed while the pigment remains the same. Airbrushing a model typically consumes two to three times what brushing the same area would.
What ventilation do I need?
Good ventilation for any solvent-based paint or thinner, and a spray booth extracting outdoors for airbrushing. Airborne paint particles and solvent vapour are both respiratory hazards, and a suitable mask matters more with an airbrush than a brush. This is the one part of the hobby where the safety guidance is not optional.
How do I store part-used paint?
Sealed, upright, and with the rim cleaned before closing so the lid seats properly — dried paint on the rim is why pots dry out. Acrylics benefit from a stainless ball or two for mixing. Custom mixes should go into a sealed labelled jar with the recipe written on it.
Is what I enter stored?
No. Figures are processed in your browser and never transmitted or retained.
Related tools
References
- Health and Safety Executive — spray painting, solvent exposure and respiratory protection
- GOV.UK — chemical labelling and safe disposal of paints and solvents
Sources are checked at publication and can change — how I choose and check references.