Paint Calculator

How many gallons of paint and primer a room needs from its size, ceiling height, doors, windows and coats, rounded to what you actually buy.

Rolling paint onto a room wall with an extension pole A room being repainted: the edges are already cut in with a brush and the trim is taped. A roller on an extension pole loads from a tray, lays paint on the wall in a W pattern, fills in the section with straight vertical passes and returns to the tray. Wet paint looks darker and dries to the finished colour. A window lights the room, the floor is covered with a canvas drop cloth, and a step ladder holds a cutting pail.

Prefer your local store? Enter its prices for a cost estimate.

Paint reference

½″ FINISH COAT 2 · SETS THE SHEENFINISH COAT 1 · 4 MIL WET, 1.5 DRYPRIMER · SEALS PAPER AND MUDJOINT COMPOUND, FEATHERED½″ GYPSUM BOARD2× STUD, SCREW SET JUST BELOW FACE
Typical finish on new drywall. Film thickness exaggerated; spread rate and recoat time vary, so check the can.

Coverage per gallon

Smooth, primed drywall
350–400 ft²
Bare drywall, PVA primer
300–400 ft²
Orange peel or knockdown
250–325 ft²
Flat ceiling paint
350–400 ft²
Brick, block, rough plaster
150–250 ft²

Coats

Same color, sound paint
1 coat
Color change
2 coats
New drywall or patches
primer + 2
Dark to light
tinted primer + 2
Water, smoke, marker stains
stain-block primer

Sheen and where

Ceilings
flat
Bedrooms, living rooms
matte / eggshell
Halls, kids' rooms
eggshell / satin
Kitchens, bathrooms
satin
Trim and doors
semi-gloss

Timing, latex at 70 °F

Dry to touch
≈ 1 h
Recoat
2–4 h
Recoat, oil-based
16–24 h
Pull tape
when touch-dry
Full cure, washable
2–4 weeks

Safety Homes built before 1978 may have lead paint. Test before you sand or scrape, keep the room ventilated, and keep children and pets out while you work.

Full notes
  • One gallon covers roughly 350-400 sq ft per coat on smooth, primed walls; textured or porous surfaces drink more.
  • Plan on two coats of finish. Use primer over bare drywall, patches, stains, or when going from dark to light.
  • Standard door about 20 sq ft, window about 15 sq ft; subtract them if they are large, ignore them if you are unsure.
  • Ceilings take roughly the same coverage per gallon but are usually painted a separate flat white; this calculator lists them separately.
  • Buy all the paint for one room at once, or box (mix) the cans together, so the color matches.

Planning a bigger project?

Drywall CalculatorSheets of 4x8, 4x10 or 4x12 drywall for walls and ceilings, plus screws, tape and joint compound.Flooring CalculatorSquare feet, boxes and underlayment for laminate, vinyl plank, engineered or solid hardwood, with waste based on the layout.Project: Refresh a RoomAll the calculators for this job in order.

Common room sizes

Drag to change the size
12 × 14 ft168 ft²
12 × 14 ft room2.1 gal
5 × 8 ft15 × 20 ft

Drag the corner of the shape or the slider. Grid squares are 2 ft. Tap a result to load it into the calculator.