Paint Quantity Calculator
Work out how many litres or gallons of paint a room needs from its dimensions, the openings and the number of coats.
At a glance
- What you enter
- Room length, Room width, Ceiling height, Number of coats, Coverage on the tin, Doors to deduct, Windows to deduct, Tin size
- What you get
- Paintable wall area, Paintable wall area, Paint for one coat, Paint for all coats, Paint with a small reserve, Paint for all coats, Tins to buy, Paint you will actually own, Surplus paint, Square metres covered per litre with all coats
- Formula shown
- Yes, every step, right below your results.
- Cost and privacy
- Free, no account needed, and nothing you type is stored.
See worked examples ↓ Read the FAQ ↓ Share this calculator ↓
Results are estimates for general information only, always verify with a professional or official source before acting on them.
How to use the Paint Quantity Calculator
- 1 Enter Room length (m), Measure the longest wall, then the wall at right angles to it.
- 2 Enter Room width (m)
- 3 Enter Ceiling height (m), Floor to ceiling. Victorian rooms are often 2.7 m or more, which changes the answer noticeably.
- 4 Enter Number of coats, Two for a colour change. Three when going from a strong colour to white or over fresh filler.
- 5 Enter Coverage on the tin (sq m per litre), Emulsion is typically 10 to 12 square metres per litre per coat. Use the figure printed on your own tin.
- 6 Enter Doors to deduct, A standard interior door is about 1.9 square metres, both faces.
- 7 Enter Windows to deduct, A standard window is about 1.4 square metres.
- 8 Enter Tin size (litres), Common sizes are 1 litre, 2.5 litres and 5 litres.
- 9 Press Calculate. You get Paintable wall area, Paintable wall area, Paint for one coat, Paint for all coats, Paint with a small reserve, Paint for all coats, Tins to buy, Paint you will actually own, Surplus paint, Square metres covered per litre with all coats, and every intermediate step stays visible under "How is this calculated?"
- 10 Change one number at a time to see what moves the result, that is usually the most useful thing a calculator can tell you.
Worked examples
Real numbers run through this calculator. Open any example to load it into the form above and change it.
A 4 by 3 metre room, two coats
One door, one window, 2.4 metre ceiling, emulsion at 11 square metres per litre, 2.5 litre tins.
You enter
- Room length
- 4 m
- Room width
- 3 m
- Ceiling height
- 2.40 m
- Number of coats
- 2
- Coverage on the tin
- 11 sq m per litre
- Doors to deduct
- 1
- Windows to deduct
- 1
- Tin size
- 2.50 litres
You get
- Paintable wall area
- 30.30 sq m
- Paintable wall area
- 326.15 sq ft
- Paint for one coat
- 2.75 L
- Paint for all coats
- 5.51 L
- Paint with a small reserve
- 5.78 L
- Paint for all coats
- 1.46 US gal
- Tins to buy
- 3
- Paint you will actually own
- 7.50 L
- Surplus paint
- 1.99 L
- Square metres covered per litre with all coats
- 5.50 sq m
About 30.3 square metres of wall, 2.75 litres per coat, 5.5 litres in total, so three tins and a little left over for touch ups.
A large living room going white
A 6 by 4.5 metre room with three windows and two doors, three coats at 10 square metres per litre.
You enter
- Room length
- 6 m
- Room width
- 4.50 m
- Ceiling height
- 2.70 m
- Number of coats
- 3
- Coverage on the tin
- 10 sq m per litre
- Doors to deduct
- 2
- Windows to deduct
- 3
- Tin size
- 5 litres
You get
- Paintable wall area
- 48.70 sq m
- Paintable wall area
- 524.20 sq ft
- Paint for one coat
- 4.87 L
- Paint for all coats
- 14.61 L
- Paint with a small reserve
- 15.34 L
- Paint for all coats
- 3.86 US gal
- Tins to buy
- 4
- Paint you will actually own
- 20.00 L
- Surplus paint
- 5.39 L
- Square metres covered per litre with all coats
- 3.33 sq m
The third coat and the larger openings push a big room to two 5 litre tins, which is the moment to check whether a tinted primer would save a coat.
A small box room in a similar colour
A 2.5 by 2 metre room at 2.3 metres, one coat over the same colour.
You enter
- Room length
- 2.50 m
- Room width
- 2 m
- Ceiling height
- 2.30 m
- Number of coats
- 1
- Coverage on the tin
- 12 sq m per litre
- Doors to deduct
- 1
- Windows to deduct
- 1
- Tin size
- 1 litres
You get
- Paintable wall area
- 17.40 sq m
- Paintable wall area
- 187.29 sq ft
- Paint for one coat
- 1.45 L
- Paint for all coats
- 1.45 L
- Paint with a small reserve
- 1.52 L
- Paint for all coats
- 0.38 US gal
- Tins to buy
- 2
- Paint you will actually own
- 2.00 L
- Surplus paint
- 0.55 L
- Square metres covered per litre with all coats
- 12.00 sq m
Under two litres, so two 1 litre tins. The 5 percent reserve is what covers the cutting in around the frames.
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