Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Paint needed
2.00
Estimated paint cost
$90
Paintable wall area
312
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One click, a permanent link with your numbers baked in.
How to use this
- 1Enter room length (ft).
- 2Enter room width (ft).
- 3Enter ceiling height (ft).
- 4Enter doors and windows area (sqft).
- 5Enter number of coats.
- 6Enter price per gallon ($).
- 7Read your paint needed on the right — it updates as you type.
- 8Hit Share to keep the scenario or send it to someone.
About this calculator
A 10x12 bedroom or office is one of the most common room sizes to paint. This calculator defaults to those dimensions with 8-foot ceilings, two coats, and standard door/window deductions, returning the gallons needed and total paint cost.
Worked example
Using the values the calculator loads with:
Inputs
- Room length: 12 ft
- Room width: 10 ft
- Ceiling height: 8 ft
- Doors and windows area: 40 sqft
- Number of coats: 2
- Price per gallon: 45 $
Results
- Paint needed: 2
- Estimated paint cost: $90
- Paintable wall area: 312
What each field means
Inputs
- Room length (ft)
- The room length used in the calculation, measured in ft. Starts at 12 ft so you have a working example on load.
- Room width (ft)
- The room width used in the calculation, measured in ft. Starts at 10 ft so you have a working example on load.
- Ceiling height (ft)
- The ceiling height used in the calculation, measured in ft. Starts at 8 ft so you have a working example on load. Accepted range: 6–14 ft.
- Doors and windows area (sqft)
- The doors and windows area used in the calculation, measured in sqft. Starts at 40 sqft so you have a working example on load.
- Number of coats
- The number of coats used in the calculation. Starts at 2 so you have a working example on load. Accepted range: 1–3.
- Price per gallon ($)
- The price per gallon used in the calculation, measured in $. Starts at 45 $ so you have a working example on load.
Results
- Paint needed
- Returned as a decimal number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Estimated paint cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Paintable wall area
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How many gallons of paint for a 10x12 room?
With 8-foot ceilings and two coats, about 1.5-2 gallons, depending on door/window area — most people round up to buy a full gallon can.
Does this include the ceiling?
No, this covers wall area only; add ceiling square footage (length × width) separately if painting the ceiling too, since ceiling paint often differs from wall paint.
Why does paint coverage vary from the 350 sqft/gallon standard?
Textured walls, dark color changes, and unprimed drywall all reduce actual coverage, sometimes to 250-300 sqft per gallon, so buy slightly more than the calculated minimum.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). 10x12 Room Paint Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/10x12-room-paint-calculator
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/10x12-room-paint-calculator" target="_blank" rel="noopener">10x12 Room Paint Calculator — RevenueLab</a> (2026).</p>
Source: [10x12 Room Paint Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/10x12-room-paint-calculator) (2026).