Rex says
Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.
Try a scenario
Click to load — tweak from there.Inputs
Result
Gallons of ceiling paint
1
Ceiling area
180
sq ft
Exact gallons before rounding
0.51
Psst — share this and help Rex grow
One click, a permanent link with your numbers baked in.
How to use this
- 1Enter room length (ft).
- 2Enter room width (ft).
- 3Enter number of coats.
- 4Enter coverage per gallon (sq ft).
- 5Read your gallons of ceiling paint on the right — it updates as you type.
- 6Hit Share to keep the scenario or send it to someone.
About this calculator
Ceiling paint is a distinct product from wall paint — usually flat-finish and thicker to reduce drips when rolling overhead — but it shares the same 350-400 sq ft per gallon coverage rate as standard interior paint. Because ceilings are simple rectangles with no doors or windows to subtract, this calculator is simpler than a wall paint tool: multiply room length by width to get square footage, multiply by the number of coats (one coat is common for ceilings already painted white, two for a color change or heavy stains), then divide by coverage per gallon and round up. Ceilings often get skipped or under-planned because people assume 'it's just one surface,' but a 12x15 room's ceiling is 180 square feet, which alone can require a full gallon for two coats. This tool also accounts for the fact that many painters prefer to buy a full gallon even for small rooms since ceiling paint is harder to blend if you run out mid-coat and have to reopen a new can with a slightly different batch tint.
Worked example
Using the values the calculator loads with:
Inputs
- Room length: 15 ft
- Room width: 12 ft
- Number of coats: 1
- Coverage per gallon: 350 sq ft
Results
- Gallons of ceiling paint: 1
- Ceiling area: 180
- Exact gallons before rounding: 0.51
What each field means
Inputs
- Room length (ft)
- The room length used in the calculation, measured in ft. Starts at 15 ft so you have a working example on load.
- Room width (ft)
- The room width used in the calculation, measured in ft. Starts at 12 ft so you have a working example on load.
- Number of coats
- The number of coats used in the calculation. Starts at 1 so you have a working example on load. Accepted range: 1–3.
- Coverage per gallon (sq ft)
- The coverage per gallon used in the calculation, measured in sq ft. Starts at 350 sq ft so you have a working example on load. Accepted range: 200–450 sq ft.
Results
- Gallons of ceiling paint
- Returned as a whole number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Ceiling area
- sq ft
- Exact gallons before rounding
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
Does ceiling paint cover the same area as wall paint?
Yes, roughly the same 350-400 sq ft per gallon, though ceiling paint is formulated thicker to minimize drips when rolling overhead, which can slightly reduce effective coverage versus a thin wall paint.
Do ceilings need two coats?
One coat is often enough for a ceiling repainted the same white over an already-painted, unstained surface; two coats are needed for color changes, water stains, smoke damage, or new drywall that hasn't been painted before.
Should I use flat or eggshell paint for ceilings?
Flat is standard for ceilings because it hides surface imperfections and doesn't reflect light in a way that highlights roller marks, while eggshell or satin ceilings are sometimes used in bathrooms for moisture resistance.
Can I use leftover wall paint on a ceiling?
Technically yes if it's the same finish, but ceiling-specific paint is thicker and drips less when applied overhead, so it's usually worth buying the dedicated product rather than repurposing wall paint.
Accuracy and limitations
- Estimates assume standard, average conditions — local rules, pricing, and materials vary.
- Results are rounded for readability; add a buffer before ordering, booking, or committing.
- Double-check anything with a real cost attached against a local quote.
Related tools
Interior Paint Gallons Calculator
Convert wall square footage into the exact number of gallons and coats you need to buy.
Primer Gallons Calculator
Work out how much primer to buy before you ever open the topcoat can.
Exterior Paint Gallons Calculator
Estimate gallons of exterior house paint from wall dimensions and siding texture.
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Ceiling Paint Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/ceiling-paint-calculator
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/ceiling-paint-calculator" target="_blank" rel="noopener">Ceiling Paint Calculator — RevenueLab</a> (2026).</p>
Source: [Ceiling Paint Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/ceiling-paint-calculator) (2026).