STANDARD
$0
Enough for one room, done properly. Ads appear on this tier.
- Quick Calc, as often as you like
- One saved project with one room
- All the deductions and coverage rates
- Ceiling and trim
- Imperial and metric
ClearStack Apps
$3.99 UNLOCK Get PaintCalc
ROOM PAINT CALCULATOR
PaintCalc
Room Paint Calculator
The doors and windows are the whole point.
Anyone can multiply a wall. PaintCalc takes the openings back off, applies the coverage rate for the finish and the surface you are actually painting, adds a touch-up margin, and rounds to tins you can carry out of the shop.
Free to use.
$3.99 one-time unlock.
Where the number comes from
An 18 by 15 ft room with 8 ft walls, two ordinary doors and three ordinary windows, two coats of eggshell over paint that is already there. Every line below is a step the app takes, in the order it takes it.
Change the finish to semi-gloss and the coverage drops to 350 sq ft a gallon. Change the surface to bare brick and it drops to 175. Same room, twice the paint. That is why the surface question is on the screen and not buried in a help page.
- Walls — 2 × (18 + 15) × 8 ft 528 sq ft
- 2 standard doors at 20 sq ft 40 sq ft
- 3 standard windows at 15 sq ft 45 sq ft
- Net wall area 443 sq ft
- 2 coats 886 sq ft to cover
- Eggshell on previously painted, 400 sq ft per gallon 2.22 gal
- 10% for touch-ups 2.44 gal
BUY 3 gallons rounded up from 2.44 — 3 × gallon
The coverage rates it works from
Square feet per gallon, for every finish on every surface the app knows about. These are what the divide in the ledger uses, and they are the reason a bathroom in semi-gloss costs more than a bedroom in flat.
| Finish | Smooth drywall | Textured drywall | Bare wood | Previously painted | Brick | Stucco |
|---|---|---|---|---|---|---|
| Flat / Matte | 400 | 300 | 300 | 400 | 200 | 200 |
| Eggshell | 400 | 300 | 300 | 400 | 200 | 200 |
| Satin | 400 | 300 | 300 | 350 | 200 | 200 |
| Semi-gloss | 350 | 250 | 300 | 350 | 175 | 175 |
| Gloss | 350 | 250 | 300 | 350 | 175 | 175 |
| Primer | 300 | 250 | 250 | 350 | 200 | 200 |
If the tin in your hand quotes something else, type it in and the app uses yours instead. Published rates assume a wall in reasonable condition, so a heavy texture or a dark colour going light will still take more. It reduces the guesswork, it does not remove the second trip.
On the phone, and on a tablet
What else it does
Quick Calc
One screen, no saving, no project. Dimensions in, gallons out, for when you are standing in the aisle deciding.
Ceilings, on their own numbers
Flat by default and usually one coat. Area comes from the room unless you type it, and it is totalled separately so you do not buy ceiling white by accident.
Trim and baseboard
Linear feet times the width of the board, in semi-gloss at two coats unless you say otherwise. Small area, awkward arithmetic.
Odd-shaped rooms
Enter the perimeter instead of length and width, or skip straight to a square-foot figure you measured yourself.
Shopping list
Every room in the project rolled into what to actually buy, grouped by wall, ceiling and trim paint, with the colour name and which rooms it is for. Share it as plain text to whoever is going.
Cost estimator
Paint at your price per gallon, plus an hourly rate and hours if you are quoting, plus supplies. It breaks the total down line by line.
Imperial or metric
Feet and gallons, or metres and litres, across dimensions, areas and quantities.
Ten languages
English, Spanish, French, German, Portuguese, Hindi, Arabic, Japanese, Korean and Chinese, throughout the app rather than only on the store page.
Two ways to use it
PREMIUM
$3.99one-time
For a whole house, or for quoting one. Everything above, and:
- As many projects and rooms as you need
- Paint shopping list, shareable
- Cost estimator with labour and supplies
- No ads
One payment. Nothing renews.
Questions
How does it work out the wall area?
Three ways. Length by width by wall height for a rectangular room, perimeter by height for an odd-shaped one, or type the square footage straight in if you have already measured it.
How much does it take off for a door or a window?
A standard door is 20 sq ft and a large one is 40. A standard window is 15 sq ft and a large one is 25. You can add your own deduction in square feet for anything unusual.
Where do the coverage numbers come from?
Published coverage figures for each paint finish on each surface, from flat on smooth drywall at 400 sq ft per gallon down to gloss on brick at 175. You can override the rate if your tin says something different.
Why does it tell me to buy more than it calculated?
It adds ten per cent for touch-ups, then rounds up to what you can actually buy: a quart, a gallon, or whole gallons after that.
Does it do ceilings and trim?
Yes, each with its own finish and coat count. Ceiling area comes from the room dimensions unless you enter it. Trim is worked from linear feet and the width of the board.
Does it work in litres and metres?
Yes. Switch units in settings and dimensions, areas and quantities all change over.
What does the $3.99 unlock add?
More than one project and more than one room per project, the cost estimator and the shopping list, and it removes the ads. Quick Calc is unlimited either way.
Want the arithmetic on its own? How much paint do I need, worked through.
Measure once, buy once
Two minutes with a tape and you know exactly what to put in the trolley.