A room-size estimate · 01
Ceiling paint calculator
Measure the floor, choose the texture, and get the gallons and cans for the job.
- Last checked: October 10, 2026
- By the Paint Gallons editorial team
- Method checked against the sources below
- Free · no sign-up · your inputs stay in your browser
Paint Gallons editorial review
Written and reviewed by the Paint Gallons editorial team. Last checked October 10, 2026 against the linked manufacturer references.
Estimate your ceiling paint
Runs in your browserYour result will appear hereEnter your room’s length and width to see how much ceiling paint you need.
A flat ceiling has the same area as the floor below it, so all you need is the room’s length and width. Choose how many coats you plan and how textured the ceiling is, and the calculator shows the paint, the cans and the working.
- Smooth, knockdown and popcorn ceilings
- Imperial or metric
- Optional 10% extra for touch-ups
How this is calculated
Ceiling area = room length × room width. Paint = ceiling area × coats ÷ (coverage × texture factor). For example, a 12 × 10 ft room has 120 sq ft of ceiling: 120 sq ft × 2 coats ÷ 400 sq ft per gallon = 0.6 gal.
The ceiling estimate and examples were written and reviewed by the Paint Gallons editorial team. The coverage assumption is checked against manufacturer product information; the formula is also compared with the linked paint calculator.
gallons = length × width × coats ÷ (coverage × texture factor)
Assumptions
- Default coverage is 400 sq ft per gallon (10 m² per litre in metric), the smooth-surface figure most ceiling paints print on the can.
- Texture factors come from published coverage figures: smooth 1; light texture or knockdown 0.875 (350 ÷ 400 sq ft per gallon, CalculatorSoup’s figure for textured ceilings); popcorn or acoustic 0.625 (250 ÷ 400, HomeGrail’s figure for popcorn).
- The ceiling is flat and rectangular. For a sloped or vaulted ceiling, measure the sloped surface instead of the floor.
- The paint is rounded to one decimal place before cans are planned. In imperial, buy 5-gallon buckets first, then 1-gallon cans, then quarts: a remainder over 0.5 gal becomes another gallon, up to 0.5 gal becomes 1 or 2 quarts, and five gallon cans become one more bucket. In metric, buy 5 L cans, then 2.5 L and 1 L cans.
- Add 10% extra multiplies the paint by 1.1 before rounding. Primer is not included.
Frequently asked questions
How much paint do I need for a 12 × 12 ceiling?
A 12 × 12 ft ceiling is 144 sq ft. Two coats at 400 sq ft per gallon need 144 × 2 ÷ 400 = 0.72 gallons, about 0.7 gal, so one gallon can is enough on a smooth ceiling.
Does a popcorn ceiling take more paint?
Yes. The bumps add surface and soak up paint, so a gallon covers about 250 sq ft instead of about 400 on a smooth ceiling. The calculator multiplies the can’s coverage by 0.625 for popcorn and 0.875 for a light or knockdown texture.
How many coats does a ceiling need?
Two coats are the safe plan for a color change, new drywall or a stained ceiling. A fresh coat of the same white over a clean, sound ceiling often needs only one.
Is the ceiling area the same as the floor area?
For a flat ceiling, yes: both are length × width. Sloped, vaulted or tray ceilings have more surface than the floor, so measure each sloped plane and add them up.
Should I buy extra ceiling paint?
Tick Add 10% extra to allow for cutting in, roller loss and touch-ups. The cans you buy already round the estimate up, and leftover paint keeps for touch-ups if the lid is sealed.
Painting the walls too?
The main paint calculator works out the walls, doors and windows, and can add the ceiling.
More paint calculators
Guides for this job
How paint coverage works
What the square feet per gallon figure on a paint can means, why new drywall and texture lower it, and how to turn it into gallons.
5 min readUpdated October 10, 2026
How much paint for a ceiling
Measure a flat or sloped ceiling, pick a ceiling paint and estimate gallons for smooth and popcorn ceilings, with a worked 12 × 10 ft example.
6 min readUpdated October 10, 2026