How much paint for a 20×20 ceiling?
A 20 × 20 ft ceiling (400 square feet) needs about 2.29 gallons of ceiling paint for two coats on a smooth surface: 2 gallons + 2 quarts.
How to work it out
- 20 ft × 20 ft = 400 sq ft of ceiling
- 400 sq ft × 2 coats ÷ 350 sq ft/gal = 2.29 gal → buy 2 gallons + 2 quarts
Four hundred square feet is a great room, an open kitchen and family area, a basement rec room or the ceiling of a two-car garage. At this size the paint is the easy part; keeping a wet edge across a ceiling that takes most of an hour per coat is the hard part.
Adjust for your project
More options: Coverage · Extra (spray loss, touch-up stock)
- Ceiling paint needed
- 2.29 gal (8.65 L)
- Cans of the size you chose
- 3 cans · 1-gallon
- Ceiling area
- 400 sq ft
- Paint per coat
- 1.14 gal
- Coverage used
- 350 sq ft/gal
- Using a planning coverage for this surface. The figure on your can is better: type it under More options.
- On a big ceiling, keep a wet edge: roll in sections a few feet wide across the short direction of the room and finish each strip before the edge dries.
Ceiling paint by room width (same length and coats)
| Room width | Ceiling area | Ceiling paint needed | Buy (gallons and quarts) |
|---|---|---|---|
| 8 ft | 160 sq ft | 0.91 gal | 1 gallon |
| 10 ft | 200 sq ft | 1.14 gal | 1 gallon + 1 quart |
| 12 ft | 240 sq ft | 1.37 gal | 1 gallon + 2 quarts |
| 14 ft | 280 sq ft | 1.6 gal | 2 gallons |
| 16 ft | 320 sq ft | 1.83 gal | 2 gallons |
| 20 ft | 400 sq ft | 2.29 gal | 2 gallons + 2 quarts |
What to know about a 20×20 ceiling
- 2.29 gallons smooth, about 3.2 textured. Two coats at 350 sq ft per gallon, or at 250 for a textured or popcorn finish. Two gallons and two quarts, or three gallons with a spare for the garage.
- Garage ceilings are often unfinished or only taped; bare drywall paper and mud soak up the first coat, so prime first (see primer for 1,000 sq ft of new drywall for the rate) or plan the first coat at the low end of the range.
- Work in strips. Roll 4–5 ft wide strips across the room, cutting in just ahead of the roller, and don’t stop for a break halfway across a strip. A thicker-nap cover holds more paint per dip.
- Lighting. Look at the ceiling from a low angle with a work light between coats; misses and thin spots are hard to see straight up.
A ceiling this size is also where a drywall lift earns its rent if you are hanging new board first: how many sheets of drywall for a 2 car garage covers the board.
Different size? Use the full Ceiling Paint Calculator.
What you’ll need
- Extension pole (4–8 ft)Budget price
Rolls ceilings and tall walls from the floor, with more even pressure than reaching from a ladder.
See options on Amazon (opens in a new tab) - 5-gallon bucket and roller gridBudget price
Once a job needs more than two gallons, boxing the paint in a bucket keeps the color consistent and a grid replaces the tray.
See options on Amazon (opens in a new tab) - Roller covers, 3/8 in and 1/2 in napBudget price
Shorter nap for smooth walls and trim-adjacent work, longer nap for textured ceilings and rough siding. A fresh cover per color saves cleanup.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
How much paint for a 20x20 popcorn ceiling?
About 3.2 gallons for two coats at 250 sq ft per gallon: 3 gallons + 1 quart.
How much paint for one coat on a 20x20 ceiling?
About 1.14 gallons: 1 gallon + 1 quart.
Other common sizes
- How much paint for a 12x12 ceiling — 0.82 gal: buy 1 gallon
- How much paint for a 10x10 ceiling — 0.57 gal: buy 1 gallon
Sources
- Behr, Premium Plus Interior Ceiling Flat Paint & Primer (No. 558), technical data sheet (opens in a new tab) — Coverage 250–400 sq ft per gallon depending on application method and porosity; formulated for textured, popcorn and acoustic ceilings.
- Sherwin-Williams, ProMar 200 Zero VOC Interior Latex Flat (B30 series), product data sheet (opens in a new tab) — Coverage 350–400 sq ft per gallon at 4 mils wet; sheen 1.5–3.5 units at 85°.
- US EPA, Learn About Asbestos (opens in a new tab) — Lists textured paint and patching compounds used on walls and ceilings among older products that may contain asbestos.