Show the formula and working
This paint cost calculator works out what the paint for a decorating job will cost, including whole tins, primer and sundries, for DIY decorators in the UK, Ireland and the eurozone. Enter the area, coats, the coverage and price of your chosen tin, and it shows a total budget and a cost per square metre in pounds or euros.
Quick answer: the paint cost calculator divides area times coats by the tin’s coverage to get litres, rounds up to whole tins, multiplies by the tin price, then adds primer and sundries. For 45 m², two coats at 12 m² per litre and 5 litre tins at £35, the total is £90.
What Is a Paint Cost Calculator?
A paint cost calculator is a tool that turns the area you want to paint into a materials budget, based on how many tins you must actually buy.
The formula runs in four steps. Multiply the area by the number of coats and divide by the coverage per litre to get litres. Divide the litres by the tin size and round up, because shops do not sell part tins. Multiply the tins by the price per tin. Finally, add any primer or mist coat and your sundries, such as rollers, brushes, masking tape and filler.
The paint cost calculator also divides the total by the area to give a cost per m², which makes it easy to compare two paints or check a decorator’s materials line.
How Do You Use the Paint Cost Calculator?
- Enter the area to paint in m² or ft². If you only know the room size, get the wall area from the paint calculator first.
- Choose 1, 2 or 3 coats. Two is standard for walls.
- Enter the coverage in m² per litre from the tin or the product page.
- Select the tin size you plan to buy: 1, 2.5, 5 or 10 litres.
- Type the price of one tin from your retailer. The default of £35 is only an example.
- Add the cost of primer or mist coat paint if you need it, and your rollers, brushes, tape and filler.
- Read the total cost, the cost per m² and the breakdown of tins, paint and extras.
How Much Does Paint Cost for a Room?
The paint for an average UK double bedroom usually costs the price of one 5 litre tin plus one small tin, because 33 m² of wall over two coats needs about 5.5 litres at 12 m² per litre.
Prices vary widely between budget, mid range, designer and trade paints, and they change often, so we do not quote a national average. Instead, the paint cost calculator uses the tin price you see on the shelf or website today. Run it twice with two different paints and you will see straight away whether a dearer tin with better coverage is actually cheaper per m².
Sundries are easy to forget. A roller set, a cutting in brush, tape, dust sheets and a tub of filler can add a noticeable amount to a small job, which is why the tool includes them as a separate line.
Is It Cheaper to Buy Bigger Tins of Paint?
Usually yes, the price per litre falls as the tin gets bigger, but a big tin only saves money if you will use most of it.
The table shows the same 45 m² job priced with four tin sizes. The prices are made up examples to show how the paint cost calculator rounds up; replace them with real prices from your retailer.
| Tin size | Example price | Price per litre | Tins for 7.5 L | Total with £20 sundries |
|---|---|---|---|---|
| 1 litre | £12 | £12.00 | 8 | £116.00 |
| 2.5 litres | £22 | £8.80 | 3 | £86.00 |
| 5 litres | £35 | £7.00 | 2 | £90.00 |
| 10 litres | £55 | £5.50 | 1 | £75.00 |
Why Does Coverage Change the Cost So Much?
Coverage sets how many litres you buy, so a paint that covers 14 m² per litre needs about 14% fewer litres than one that covers 12 m² per litre for the same wall.
Manufacturers publish their figures. Dulux, for example, lists up to 14 m² per litre for Dulux Matt, and its Dulux Trade Vinyl Matt Light & Space claims up to 17 m² per litre. Those are best case numbers on smooth, sealed walls. Using a slightly lower figure in the paint cost calculator gives a budget you are less likely to overshoot.
Tin rounding can hide the difference on small jobs. Two paints may both need two 5 litre tins, but on a whole house the higher coverage paint can save several tins.
Worked Example: Tom’s Lounge Budget
Tom is repainting the walls of his lounge in Cardiff. The paint calculator gave him 45 m² of wall once the bay window and door were taken off. His chosen matt emulsion covers 12 m² per litre and costs £35 for a 5 litre tin at his local store. He already owns brushes, so he sets sundries to £20 for a new roller sleeve, tape and filler.
- Litres: 45 m² x 2 coats / 12 = 7.5 litres
- Tins: 7.5 / 5 L = 1.5, rounded up to 2 tins
- Paint: 2 x £35.00 = £70.00
- Total: £70.00 + £0.00 primer + £20.00 sundries = £90.00, or £2.00 per m²
Tom then checks the 2.5 litre tin of the same paint at £22. Three of those cost £66, so the paint cost calculator shows a total of £86 and £1.91 per m², saving £4 with less paint left over.
What Else Should a Painting Budget Include?
A full DIY budget should include primer or mist coat paint, sundries, and any paint for ceilings and woodwork, which this tool prices separately when you run it again for each paint.
- New plaster needs a thinned mist coat. Dulux suggests about ten parts emulsion to one part water, so add the cost of that paint in the primer box.
- Ceilings usually use a different white. Work out the litres with the ceiling paint calculator, then price that tin here.
- Woodwork and radiators need trim paint such as eggshell or satin, usually sold in smaller tins than wall emulsion.
- If you are hiring a decorator, materials are only part of the quote. Labour and preparation time are separate, and the painting time calculator helps you judge the hours.
- In older homes, budget for lead safe preparation. The HSE notes that lead pigments were widely used in household paints until the 1960s, so wet sanding and dust sheets you can throw away are worth the small extra cost.
For eurozone users, switch the currency to euro. The formula is the same; only the symbol and your tin prices change.
Common Mistakes When Budgeting for Paint
- Pricing litres instead of tins. Shops sell whole tins, so 5.5 litres of a paint sold only in 5 litre tins costs two tins. The paint cost calculator always rounds up for this reason.
- Comparing tin prices without checking coverage. A cheaper tin that covers less can cost more per m² once you need an extra tin or coat.
- Forgetting the second coat. It doubles the paint, and therefore roughly doubles the paint line of the budget.
- Leaving out primer on bare plaster, new wood or stains, which can mean a second trip to the shop mid job.
- Splitting the order. Buying all the tins of a mixed colour at once keeps the shade consistent and avoids a second delivery charge.
A simple habit avoids most of these: measure first, run the area through the paint cost calculator with real prices from two retailers, and buy everything in one order. If the total looks high, try a larger tin size or a paint with better stated coverage before cutting corners on preparation.
Paint Cost Calculator FAQs
How do I calculate the cost of painting a room?
Find the wall area, multiply by the coats, divide by the coverage per litre, and round up to whole tins. Multiply by the tin price, then add primer and sundries. The paint cost calculator does each step and shows the working.
How many tins of paint do I need for 45 m²?
For two coats at 12 m² per litre, 45 m² needs 7.5 litres. That is two 5 litre tins, three 2.5 litre tins or one 10 litre tin. The cheapest option depends on the price of each size.
What is the cost per m² of paint?
It is the total materials cost divided by the area painted. In our worked example, £90 for 45 m² gives £2.00 per m². It is a useful way to compare two paints or check a decorator’s materials figure.
Is trade paint cheaper than retail paint?
Not always per tin, but some trade matts state higher coverage, so you may need fewer litres. Enter each paint’s real coverage and price into the paint cost calculator and compare the cost per m² rather than the tin price.
Should I include sundries in a paint budget?
Yes. Rollers, sleeves, brushes, masking tape, dust sheets and filler all add up, especially on a first job when you own none of them. The calculator has a separate box so they are not forgotten.
Does the paint cost calculator include labour?
No, it prices materials only: paint, primer and sundries. If you are hiring a decorator, ask for labour and materials as separate lines and compare the materials line with the calculator’s result.
Checked October 2026. Sources: Dulux and Dulux Trade product data, Dr Dulux new plaster guide, Health and Safety Executive (HSE).