30 ml tester pot: area covered by coverage and coats
Use the coverage printed on your tin. 12 m² per litre is typical for emulsion.
| Coverage on the tin | 1 coat | 2 coats | 3 coats |
|---|---|---|---|
| 10 m² per litre | 0.30 m² | 0.15 m² | 0.10 m² |
| 12 m² per litre | 0.36 m² | 0.18 m² | 0.12 m² |
| 13 m² per litre | 0.39 m² | 0.20 m² | 0.13 m² |
| 14 m² per litre | 0.42 m² | 0.21 m² | 0.14 m² |
A 30 ml tester pot: one good patch
At 12 m² per litre a 30 ml tester covers 0.36 m² in one coat, or 0.18 m² with the two coats you need to judge a colour. That is a square about 42 cm on each side, a useful patch on one wall and no more.
If you want to see the colour on two walls, in the light and in the shade, buy two pots. It takes about 33 pots to make a litre, so a tester is never the cheap way to paint anything: two coats on the walls of a 3 × 3 m room would be 143 pots.
Paint the patch on the wall itself, or on a sheet of lining paper you can move round the room, and look at it in daylight and under the lamps you use in the evening.
Worked example
30 ml is 0.03 litres. 0.03 × 12 m² per litre = 0.36 m² in one coat. Two coats halve it: 0.36 ÷ 2 = 0.18 m². The square root of 0.18 m² is about 0.42 m, so the patch is about 42 cm each way.
Other tin sizes
| Size | One coat | Two coats | Wall run, two coats (2.4 m high) |
|---|---|---|---|
| 30 ml tester | 0.36 m² | 0.18 m² | a test patch |
| 1 litre | 12 m² | 6 m² | 2.5 m |
| 2 litres | 24 m² | 12 m² | 5 m |
| 2.5 litres | 30 m² | 15 m² | 6.25 m |
| 5 litres | 60 m² | 30 m² | 12.5 m |
| 10 litres | 120 m² | 60 m² | 25 m |
For your own room use the paint calculator, which gives the litres and the tins to buy. The tin coverage chart puts 1, 2.5, 5 and 10 litre tins side by side at each coverage.
Want to change anything else? The calculator above is the full Paint Calculator (UK, litres): edit any number and the results update instantly.
Tools & materials for this project
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Frequently asked questions
How much does a 30ml tester pot cover?
About 0.36 m² in one coat at the typical 12 m² per litre, or 0.18 m² with two coats. On rough walls or dark colours, at 10 m² per litre, it is 0.30 m² in one coat.
Can I paint a wall with tester pots?
Not sensibly. Two coats on a 3 × 3 m room's walls take 4.3 litres, which is 143 pots of 30 ml. Use testers to choose, then buy a tin.
How many tester pots make a litre?
About 33 pots of 30 ml. A 1 litre tin covers 6 m² with two coats, so anything bigger than a patch is cheaper from a tin.
Related sizes and guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check the Building Regulations and your supplier's guidance before ordering.