Paint Calculator
Buying the right amount of paint the first time saves a wasted trip back to the shop and avoids the risk of a slightly mismatched top-up batch partway through a wall. Enter your room dimensions, how many doors and windows to deduct, and how many coats you're planning below to get a litres estimate.
Work out how much paint you need
Enter your room dimensions, doors/windows, and how many coats you plan to apply.
Wall area to paint (after deducting doors and windows): 33.2m²
approximately 5.5 litres of paint
A 5L can (or combination of cans) should cover this, based on average emulsion coverage of 12m² per litre per coat.
Recommended products
A few well-reviewed decorating essentials for your next paint job.
- Interior walls
£28.00
Pros
- Wipeable finish shrugs off scuffs in hallways and kids rooms
- Good one-coat opacity over most existing colours
- Covers around 32.5m² per coat
Cons
- Matt finish shows roller marks if overworked
- Exterior wood
£14.50
Pros
- Touch dry in around an hour so fences get two coats in a day
- Water repellent and rainproof in as little as 30 minutes
- Water-based formula cleans up with soap and water
Cons
- Needs reapplying yearly on south-facing fences
- Interior walls
£108.00
Pros
- Chalky, richly pigmented finish sought after by interior designers
- Low-VOC formula suited to bedrooms and nurseries
- Exceptional depth of colour in muted heritage shades
Cons
- Premium price per litre compared with high-street brands
- Mixed to order, so cannot be returned once opened
Frequently asked questions
How many coats of paint do I actually need?
Two coats is standard for most emulsions and gives an even, opaque finish, especially over a different existing colour. A single coat can work for touch-ups or when using a dedicated one-coat paint, while very dark colours or big colour changes sometimes need three coats.
Does paint coverage vary between brands?
Yes — this calculator uses an average coverage of 12m² per litre per coat, which is typical for mid-range emulsion, but budget paints can cover less (nearer 10m²/L) and premium paints can cover more (up to 14-16m²/L). Check the coverage figure on your chosen tin and adjust your estimate accordingly.
Should I paint the ceiling too?
This calculator estimates wall area only. If you're painting the ceiling as well, add its area (room length × width) separately, usually with a ceiling-specific paint that resists drips and gives a flat, non-reflective finish.
Is it better to buy slightly more paint than the estimate?
Yes — buying a little extra avoids running out mid-wall and having to colour-match a top-up later, which can leave a visible join if the batch differs slightly. Keeping leftover paint is also useful for future touch-ups.