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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.

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.

How this one works

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.

RateDefaultWhy
Coverage11 m²/LEmulsion on a sealed surface. Textured or porous walls take more.
Mist coat coverage9 m²/L
Tin size5 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
  • Tins: 5 × 5 L

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.

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