Room Paint Cost Calculator
What it costs to paint a room, including a primer coat, the tins to buy and the cost per square metre.
The quantity of paint is one question and the cost is another, because paint is sold in tins and a tin is a fixed price whatever the coverage. This calculator takes the wall area with the openings deducted, the number of top coats and any primer, the coverage on the tin and the tin size and price, and returns the litres, the whole tins to buy and the total bill. It also shows the cost per square metre, which is the figure to compare when two paints differ in price and in coverage.
At a glance
- What you enter
- Wall length, Wall height, Doors to deduct, Windows to deduct, Top coats, Primer coats, Coverage on the tin, Primer coverage on the tin, Tin size, Price per tin of top coat, Price per tin of primer, Extra for texture, absorption and touch ups, Sales tax or VAT
- What you get
- Paintable wall area, Primer needed, Top coat needed, Paint to allow for, Tins of primer to buy, Tins of top coat to buy, Total paint you will own, Surplus paint, Cost of the primer, Cost of the top coat, Total cost of the paint, Cost per square metre of wall, Litres per square metre of wall, Tins a cheaper paint would need, Cost at the cheaper coverage
- 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 Room Paint Cost Calculator
- 1 Enter Wall length (mm)
- 2 Enter Wall height (mm), Floor to ceiling. Measure between the skirting and the cornice if both are staying.
- 3 Enter Doors to deduct, About 1.9 square metres each, counting both faces of the leaf.
- 4 Enter Windows to deduct, About 1.4 square metres each for a standard window.
- 5 Enter Top coats, Two for a colour change, three going from a strong colour to white or over fresh filler.
- 6 Enter Primer coats, One over bare plaster, a filled patch or a strong colour. Set to zero for no primer.
- 7 Enter Coverage on the tin (sq m per litre), Emulsion is typically 10 to 12 square metres per litre per coat. Use the figure on your own tin.
- 8 Enter Primer coverage on the tin (sq m per litre), Primer is usually lower than the top coat, often 8 to 10 square metres per litre.
- 9 Enter Tin size (litres), Common sizes are 1 litre, 2.5 litres and 5 litres.
- 10 Enter Price per tin of top coat
- 11 Enter Price per tin of primer, Set to zero if you are not priming.
- 12 Enter Extra for texture, absorption and touch ups (%), New plaster and a strong colour underneath can add twenty percent. Five is a reasonable reserve for a sealed wall.
- 13 Enter Sales tax or VAT (%), Leave at zero if the quoted price already includes tax, or if you are not registered.
- 14 Press Calculate. You get Paintable wall area, Primer needed, Top coat needed, Paint to allow for, Tins of primer to buy, Tins of top coat to buy, Total paint you will own, Surplus paint, Cost of the primer, Cost of the top coat, Total cost of the paint, Cost per square metre of wall, Litres per square metre of wall, Tins a cheaper paint would need, Cost at the cheaper coverage, and every intermediate step stays visible under "How is this calculated?"
- 15 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 6 by 2.5 metre room, two coats and a primer
One door, two windows, 11 square metres per litre, 2.5 litre tins.
You enter
- Wall length
- 6,000 mm
- Wall height
- 2,500 mm
- Doors to deduct
- 1
- Windows to deduct
- 2
- Top coats
- 2
- Primer coats
- 1
- Coverage on the tin
- 11 sq m per litre
- Primer coverage on the tin
- 9 sq m per litre
- Tin size
- 2.50 litres
- Price per tin of top coat
- $28.00
- Price per tin of primer
- $24.00
- Extra for texture, absorption and touch ups
- 5%
- Sales tax or VAT
- 0%
You get
- Paintable wall area
- 25.30 sq m
- Primer needed
- 2.81 L
- Top coat needed
- 4.60 L
- Paint to allow for
- 7.78 L
- Tins of primer to buy
- 2
- Tins of top coat to buy
- 2
- Total paint you will own
- 10.00 L
- Surplus paint
- 2.59 L
- Cost of the primer
- $48.00
- Cost of the top coat
- $56.00
- Total cost of the paint
- $104.00
- Cost per square metre of wall
- $4.11
- Litres per square metre of wall
- 0.31 L
- Tins a cheaper paint would need
- 3
- Cost at the cheaper coverage
- $84.00
37.8 square metres of wall, 4.2 litres of primer and 6.87 of top coat. That is two primer tins and three top coat tins, about 128 in total and 3.39 per square metre.
A large living room going white
A 9 by 4 metre room at 2.7 metres with three windows and two doors, three coats.
You enter
- Wall length
- 9,000 mm
- Wall height
- 2,700 mm
- Doors to deduct
- 2
- Windows to deduct
- 3
- Top coats
- 3
- Primer coats
- 1
- Coverage on the tin
- 10 sq m per litre
- Primer coverage on the tin
- 9 sq m per litre
- Tin size
- 5 litres
- Price per tin of top coat
- $52.00
- Price per tin of primer
- $45.00
- Extra for texture, absorption and touch ups
- 10%
- Sales tax or VAT
- 20%
You get
- Paintable wall area
- 40.60 sq m
- Primer needed
- 4.51 L
- Top coat needed
- 12.18 L
- Paint to allow for
- 18.36 L
- Tins of primer to buy
- 2
- Tins of top coat to buy
- 3
- Total paint you will own
- 25.00 L
- Surplus paint
- 8.31 L
- Cost of the primer
- $90.00
- Cost of the top coat
- $156.00
- Total cost of the paint
- $295.20
- Cost per square metre of wall
- $7.27
- Litres per square metre of wall
- 0.45 L
- Tins a cheaper paint would need
- 4
- Cost at the cheaper coverage
- $208.00
About 63 square metres of wall and three coats, which is 21 litres with the reserve: five 5 litre tins of top coat plus two of primer, and the VAT on top pushes the bill past 400.
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Frequently asked questions
How much does it cost to paint a room?
Work out the paintable wall area, then the litres and the tins. A 6 by 2.5 metre room at 2.5 metres high has 42.5 square metres of wall, and one door and two windows take off 4.7, leaving 37.8 square metres. Two top coats at 11 square metres per litre is 6.87 litres, so three 2.5 litre tins, and one primer coat is another 4.2 litres, so two more tins. At 28 and 24 a tin that is about 132 for the paint, before any sealer, ceiling paint or sundries.
Do I need a primer coat?
Over bare plaster, a filled patch or a strong colour that has to be covered with a light one, a primer earns its cost by sealing the surface and reducing the number of top coats needed. Over a sound, previously painted wall in a similar colour, a primer is usually unnecessary and the money is better spent on a second top coat. Use a stain blocking primer over water marks and a knotting solution over knots in bare timber, rather than relying on extra top coats to hide them.
Is cheap paint really more expensive?
It can be. The cost that matters is the cost per square metre of finished wall, which is the tin price divided by the tin volume and the coverage. A budget emulsion at 9 square metres per litre can need a third more tins than one at 11 or 12, and often needs an extra coat as well, which cancels the saving on price. The calculator shows the same area at a coverage two square metres per litre lower so the comparison is visible rather than assumed.
Why round up to whole tins?
Because paint is sold in tins and a part tin is not available. A room needing 6.9 litres is three 2.5 litre tins, which is 7.5 litres: more than the calculation asked for, but the surplus is what covers the cutting in, a patch later, and the touch up after the furniture goes back. Buy from the same batch and keep the tin code, because a tin bought six months later may not match even if the colour name is the same.
What does this paint cost estimate leave out?
Ceilings, trim, doors, skirting, sealer, filler, masking tape, dust sheets, roller sleeves and brushes. Ceilings in particular are a large area at a different price, and they are calculated separately so the two products are not blended into one average. The estimate also assumes a sealed wall in reasonable condition. New plaster, a very porous surface or a strong colour underneath can raise consumption by twenty percent or more, so buy a spare tin for a first attempt at a colour.