How do I measure the surface area for painting?

Multiply the width by the height of each surface. For multiple canvases, add the areas together. For irregular shapes, break them into rectangles and triangles, calculate each, and add them up. Remember to include both sides if painting the edges of a canvas.

Does primer count as a coat?

No — gesso/primer is a separate run with its own coverage rate. Apply 2-3 coats of gesso before your paint coats, and run the calculator separately with the gesso paint type. Note the first gesso coat on raw cotton duck soaks in roughly twice as much as later coats (Just Paint quotes ~200 sq ft/gal first coat ≈ 5 m²/L vs ~425 sq ft/gal sealed ≈ 10 m²/L), so for a single raw-canvas coat use the Custom rate at about 5 m²/L.

How do I convert between ml and litres?

1 litre = 1000 ml. A standard artist acrylic tube is 60ml or 120ml. So 1 litre equals about 17 small tubes or 8 large tubes of paint.

ArtCalcs.uk

Paint Volume Calculator

Calculate the volume of paint needed based on surface area, number of coats and paint type.

Surface Area

Canvas/board area = width × height (one face). Add both faces if you also paint the back or edges.

Number of Coats

Paint coats only — count gesso/primer coats in a separate run.

Paint TypePer-coat rates on a smooth, sealed surface. Oil is an estimate; raw-canvas gesso first coats use roughly half — see notes below. Pick Custom… for your own m²/L.

Price per Litre (optional)

Tube prices: divide tube cost by tube litres (e.g. £9 ÷ 0.06 L = £150/L). Leave blank to skip cost.

Add 10% wastage

Adds a buffer for mixing, palette waste and uneven absorption. Adjust the multiplier in Advanced options.

How We Calculate This

Litres = (Area × Coats) ÷ Coverage rate

Wastage of 10% is added when enabled to account for mixing, palette waste and absorption variations. The multiplier is editable under Advanced options.

Coverage presets are per-coat figures for a thinly applied layer on a smooth, sealed surface. Golden / Just Paint quote 250–400 sq ft/US gallon for artist paints and mediums applied thinly — that is roughly 6–10 m²/L, which brackets the 8 m²/L acrylic default.

The 6 m²/L oil figure is an estimate (artist oils have no per-tube manufacturer coverage rate); opaque tube oils land near the bottom of the 6–10 m²/L band. Gesso 10 m²/L matches a sealed second coat — a raw cotton-duck first coat absorbs about twice as much (~5 m²/L per Just Paint), so prime in 2–3 coats or use the Custom… rate. The 12 m²/L house-paint option is a decorator wall-emulsion rate, not a tube artist-paint rate.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify quantities before purchasing materials.