Paint Estimator
Estimate total paint needed and rough cost for a house — free, instant.
Buying Paint Without Guessing
Paint stores will happily sell more cans than a job needs, and running short mid-wall means a color-match risk on the next tin. This estimator works from your actual wall area, coat count, and the coverage rate printed on your chosen paint to land on a liter figure that matches the job, plus a total cost if you know the price per liter.
Filling In the Numbers
- Enter total wall area: In square feet, ideally with door and window areas already subtracted.
- Set the number of coats: Most projects need two for even, opaque coverage.
- Enter the coverage rate: Found on the paint tin's label, in square feet per liter.
- Add a price per liter (optional): To get a total project cost alongside the liter quantity.
- Set a wastage margin: A small buffer for spillage and touch-ups.
The Calculation Behind the Result
Total wall area is multiplied by the number of coats — because each additional coat needs the same coverage rate applied again — then divided by the coverage rate to get a base liter figure. The wastage percentage is added on top of that base number, and the result is rounded up to a practical purchase quantity, since paint isn't sold in fractional liters. If a price per liter is entered, that final liter figure is multiplied through for a total cost, with a cost-per-square-foot figure broken out separately for comparing against other paint options.
Worked Example: An 800 Sq Ft Room, Two Coats
Take a room with 800 square feet of wall area, two coats planned, a paint rated at 120 square feet per liter coverage, priced at 450 per liter, with a 5% wastage margin. The base calculation is (800 × 2) ÷ 120, which comes to 13.3 liters. Adding 5% wastage brings that to exactly 14 liters, rounded up to a recommended purchase of 15 liters. At 450 per liter, that's an estimated cost of 6,300 for the full job, working out to roughly 7.88 per square foot of wall covered across both coats.
Common Situations This Covers
A homeowner repainting a single room checks the liter count before a hardware store run, avoiding both an under-buy and an unnecessary extra can. A painting contractor uses the cost output to build a quick client estimate before a formal quote. Someone repainting an entire house runs the calculation room by room, since coverage needs and wall areas differ between spaces. A property manager estimates paint costs across several rental units ahead of a turnover season, comparing the per-unit numbers side by side.
A Few Practical Notes
Coverage rates genuinely differ between paint brands and finishes — a matte paint and a high-gloss paint from the same brand can have noticeably different coverage per liter, so always check the specific tin's label rather than assuming a generic figure. Textured or unfinished walls typically soak up more paint than the label's stated coverage, which is exactly what the wastage percentage is meant to absorb. Buying one larger can instead of several smaller ones to hit the exact liter total is usually the more economical choice per liter.
What Isn't Factored In
This estimator doesn't automatically subtract door and window openings — that needs to happen in the wall area figure you enter, since the tool has no way to know your room's specific layout. It also assumes uniform coverage across the whole wall area; heavily textured accent walls, exposed brick, or porous surfaces will need more paint than a smooth painted-over wall of the same square footage.
Comparing Two Paint Options
Because this tool separates out cost per square foot, it's a quick way to compare two different paint products beyond just their sticker price per can. A premium paint priced higher per liter can still work out cheaper per square foot if its coverage rate is meaningfully better, since fewer liters are needed to cover the same wall area. Run the same wall area through the calculator once for each product's stated coverage and price, and compare the resulting cost-per-square-foot figures side by side rather than comparing can prices directly — that's usually the number that actually decides which option is better value for a specific job.
Nothing Leaves Your Browser
Every figure you enter is calculated locally in your browser — there's no upload, no account, and no record kept of your project's dimensions or budget.
What coverage rate should I use if my paint tin doesn't state one clearly?
A reasonable default for standard emulsion paint is 100-120 square feet per liter, but check the manufacturer's website for your exact product if the label is unclear.
Do textured or unfinished walls really need noticeably more paint?
Yes, porous or textured surfaces absorb more paint than a smooth previously-painted wall, so increase the wastage percentage for these surfaces rather than relying on the standard 5%.
Should primer be calculated separately from the top coat paint?
Yes, primer typically has a different coverage rate than finish paint; run this calculator once for primer liters and again for the top coat using its own coverage figure.
How much should I subtract for a standard door and window when calculating wall area?
A standard door is roughly 20 square feet and a standard window 15 square feet, though exact sizes vary; measure yours directly for the most accurate figure.
Is it more cost-effective to round up to a bigger can size?
Usually yes, since larger cans typically have a lower cost per liter than several smaller cans combined, though check your specific supplier's pricing tiers.
Does the number of coats really need to be exactly two?
Two is standard for even coverage, but a dark-to-light color change or a stained wall may need a third coat, which you can enter directly to recalculate.