All 43 tools
Internal · litres · tins
How much paint do I need?
Litres by coat and surface. Bare plaster drinks the mist coat, so that is priced separately rather than counted as one of your top coats.
Measure it
Every box has its own unit next to it.
Change the unit beside any box and the number converts. The (i) beside each question says what the box wants and where the figure usually comes from. Anything marked per cent is a percentage of the quantity above it.
Check the rates
Rates and assumptions used
These are the figures the calculator works to. Change any of them and the order list updates — your merchant’s pack sizes and your own waste allowances beat the defaults every time.
Order list
The orange figure is the one you order to. Highlighted rows are the other numbers you order to. The small print under each row is the sum that produced it, so you can check it against your own take-off. Amber rows are warnings, not quantities.
How this one works
- Net area =
walls + ceiling − openings - Top coats =
net area × coats ÷ coverage - A mist coat on new plaster is thinned emulsion and covers less
The figures the calculator works to. Every one can be changed in step 2, and your merchant’s pack sizes and your own waste allowances beat these defaults every time.
| Rate | Default | Why |
|---|---|---|
| Coverage | 11 m²/L | Emulsion on a sealed surface. Textured or porous walls take more. |
| Mist coat coverage | 9 m²/L | |
| Tin size | 5 L |
A worked example
With the defaults the page opens on:
- How much wall? 58 square metres
- How much ceiling? 24 square metres
- Doors and windows to take off? 6 square metres
- How many top coats? 2 number
- What is the surface? New plaster — mist coat needed
Paint
- Net area: 76 m² — walls + ceiling − openings
- Mist coat: 8.4 litres — thinned emulsion on new plaster
- Primer / undercoat: not needed
- Top coats: 13.8 litres — 2 coats at 11 m²/L
- Total paint: 22.2 litres — mist coat + primer + top coats, as shown
- Tins: 5 × 5 L — 22.3 L ÷ 5 L tins, rounded up
Sundries
- Filler: 2 × 1 kg — rough allowance
- Masking tape: 4 rolls
- Dust sheets: 3 no.
Change any figure above and every line recalculates; the small print under each row is the sum that produced it.
Questions people ask
How much paint do I need for a room?
Net area × coats ÷ coverage. 82 m² of wall and ceiling less 6 m² of openings, two coats at 11 m² a litre, is about 13.8 litres of top coat - and on new plaster another 8.4 litres of mist coat.
What is a mist coat and do I need one?
Thinned emulsion on new plaster, so the top coats do not peel. It covers less (9 m² a litre here) and it is counted separately rather than as one of your top coats. Choose "New plaster" and it appears.
How many tins?
The total litres ÷ the tin size, rounded up. The tin count is taken from whichever is larger of the exact total and the displayed total, so rounding can only ever order a tin more, never one fewer.
Why does the total match the rows above it?
Because the page adds the displayed figures, not the hidden exact ones - so mist coat plus top coats on screen always equals the total on screen.
Calculators for the same job
Doing this for a whole job rather than one wall? SiteLedger keeps the valuations, supplier statements, invoices and variations against the project they belong to.
Read before you order. These work out quantities, not structural design — spans, lintels, rebar and foundation depths need an engineer and Building Control sign-off. Waste allowances are defaults, not promises: awkward cuts, long runs and bad weather all eat more than 5%. Where a merchant sells whole packs, the figure is rounded up to whole packs.