Plan paint for walls and ceilings
Measure a whole room, individual walls or a ceiling, or enter a known area. Use coverage per litre or per tin to estimate paint and whole tins. Plan primer and different paint products separately.
Back to calculator ↑Measure walls and openings
Choose a whole room for a rectangular room, or individual walls for one wall, an L-shaped room or walls of different heights. Enter each wall’s width and height; the calculator adds the areas. For a ceiling alone, choose ceiling and enter its width and length.
Count the doors and windows you will not paint. The starting door (0.9 × 2 m) and window (1.2 × 1.2 m) sizes can be changed in the size settings. For mixed sizes, switch to measured total opening areas. Keep any surfaces receiving the same paint in your area, and calculate different colours or products separately.
Turn coat area into litres
If the label gives coverage per tin, select that mode and enter the tin’s litres; the calculator converts the rate for you. The calculator uses net area × coats ÷ coverage in m² per litre per coat, then applies your allowance once. It divides required litres by tin size and rounds up to whole tins. Confirm that the coverage on the label is for one coat; a two-coat system figure should not be entered as if it were one-coat coverage.
Example: a 4 × 5 m room with 2.5 m walls has 2 × (4 + 5) × 2.5 = 45 m² of gross walls. Subtract 5 m² of openings to leave 40 m². At two coats, 10 m²/L per coat and 10% allowance, required paint is 40 × 2 ÷ 10 × 1.10 = 8.8 L. With 5 L tins, the purchase is two tins, or 10 L.
Choose a realistic coverage figure
Use the selected paint’s technical sheet for the relevant surface. Porous or rough plaster, application method and covering a strong old colour can alter consumption. Replace the starting coverage with the selected paint’s label rate.
Prepare and prime the surface as the manufacturer specifies. Primer often has different coverage and pack sizes; estimate it separately rather than treating the topcoat result as an all-in paint quantity. The same applies to a separate ceiling product or a feature wall colour.
Build the purchase and budget
Whole tins may leave paint; the displayed remainder is arithmetic and may differ from what remains after the job. Enter a price per tin, labour per net m² and extras if known. The tool totals only the entered items, and labour is based on net surface area rather than multiplying by coats again.
Confirm the colour code, base and finish across all tins. Budget separately for masking, tools and wall repairs. Keep the exact colour reference and batch details for later touch-ups. If a quote includes preparation or several paint systems, compare its scope with this limited materials estimate.
Common questions
Can a different ceiling paint be included?
Calculate it separately because coverage, coats and tin size can differ.
Why does 8.8 L become a 10 L purchase?
At 5 L per tin, the calculator rounds up to two whole tins.
Does the tin count include primer?
No. It covers the one topcoat product and colour entered.
Sources and calculation guidance
Check these against your chosen product’s label and instructions.