Paint Coverage Calculator
Work out how much paint a room needs. Add doors, windows, and paint type for accurate litre and tin counts.
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How to Use the Paint Coverage Calculator
Enter the room length, width, and ceiling height. The calculator automatically computes the area of all four walls and lets you toggle off any wall you do not intend to paint. Use the doors and windows steppers to subtract standard openings from the total area. Select your paint type to set the coverage rate, choose the number of coats, and the calculator gives you the exact litres needed plus the most efficient combination of 1L, 2.5L, and 5L tins with minimum waste.
About This Tool
A practical paint coverage calculator for decorators and homeowners. Supports 8 paint types including standard emulsion (12 m²/L), budget emulsion (8 m²/L), premium one-coat (15 m²/L), gloss/satinwood (14 m²/L), smooth and textured masonry, primer, and custom rates. Individual wall toggles let you exclude walls that are already painted or will be tiled. Standard door (0.9×2.1m = 1.89 m²) and window (1.2×1.0m = 1.2 m²) sizes are auto-subtracted. The tin optimiser tests all valid combinations of 1L, 2.5L, and 5L tins and shows the least-waste option first.
Paint coverage varies significantly between types. Standard trade emulsion covers about 12 m²/L on smooth primed walls. Budget formulations cover 8 m²/L due to lower pigment content. Textured masonry paints cover as little as 5 m²/L because rough surfaces have higher effective area. This calculator uses realistic trade figures rather than optimistic manufacturer claims.
Two coats is standard for most residential work. One coat is sufficient only when repainting the same colour. Three coats is needed for light over dark or bare plaster. New plaster should receive a mist coat first. Pair with the Brick Calculator for wall construction, the Concrete Calculator for foundation volumes, or match paint swatches across formats if your designer supplied HEX values but the trade counter works in RAL.
Quick Reference Table
| Paint Type | Coverage (m²/L) | Typical Use |
|---|---|---|
| Standard emulsion | ~12 | Walls, most residential |
| Budget emulsion | ~8 | Economy, low solids |
| Premium (one-coat) | ~15 | High-solids, better opacity |
| Gloss / satinwood | ~14 | Feature walls, trim |
| Smooth masonry | ~10 | External smooth walls |
| Textured masonry | ~5 | Rough render, pebbledash |
| Primer / undercoat | ~11 | Sealing, bare surfaces |
Frequently Asked Questions
How do I calculate how much paint I need for a room?
Calculate the total wall area by adding the area of each wall (width × height) and subtracting doors and windows. Multiply by the number of coats. Divide by the coverage rate of your paint (typically 10–15 m²/L for emulsion). This calculator does all those steps automatically — enter your room dimensions and it updates instantly.
How much does a 5 litre tin of paint cover?
A 5L tin of standard trade emulsion at 12 m²/L covers approximately 60 m² per coat. A typical bedroom with 4 walls at roughly 32 m² net area would need approximately 5.3 litres for 2 coats, so a single 5L tin and one 1L tin would be the efficient choice.
Should I include the ceiling in my paint calculation?
Ceiling paint is almost always a different product from wall paint — typically a white flat matt emulsion. Calculate the ceiling separately using its own paint type and coverage rate. The ceiling toggle in this tool lets you include or exclude it from the same calculation when using the same paint.
What is the standard size of a door for paint calculations?
This calculator uses a standard door of 0.9m × 2.1m = 1.89 m² per door. This is the most common internal door size in the UK (762mm × 1981mm nominally). US standard doors are slightly different at typically 32 or 36 inches wide × 80 inches tall.
Created by The Toobits Team · Engineering & Editorial
Toobits is built, tested, and maintained by a small independent engineering team. Every tool is written in TypeScript, runs entirely in the browser, and is reviewed against its source formulas before publication.
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