ContractorHandbook

How Much Paint for a 10x12 Room?

Paint needed

1.75 gallons

A 10 by 12 room with eight foot walls, one door, two windows, two coats.

It does not stop at a number.

When the figures look right, the paint material list downloads as a real PDF with your business details on it, built inside your own browser. Nothing you type is uploaded anywhere.

doorwindowwindowheightperimeter of the room, ftnet wall area x coats / coverage per gallon = gallons
A room painted is its perimeter multiplied by its height, laid out flat, with the doors and windows taken out. Multiply by the number of coats before dividing by the coverage on the can, because two coats is two full areas of paint.

How that number is worked out

These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.

  • Room perimeter, add all walls44 ft
  • Wall height8 ft
  • Doors1
  • Windows2
  • Coats2
  • Coverage per gallon350 sq ft

Paint needed1.75 gallons

Gross wall area352 sq ft
Less doors and windows-51 sq ft
Net wall area301 sq ft
Area over 2 coats602 sq ft
Gallons, exact1.72
Buy2 gallonsor 1 five gallon pail

The material list this produces

Paint, gallons2
Primer, gallons (if bare or color change)1
Painter's tape, rolls1

Coats compared

Coats is the input people get wrong, usually by hoping. Same room, one coat to three.

CoatsPaint needed
1 coat1 gallon
2 coats1.75 gallons
3 coats2.75 gallons

What else matters here

One and three quarter gallons over two coats, which is as close to two gallons as a room gets without needing a third. There is no margin here for a mistake, a spill or a wall that drinks more than expected.

The wall that drinks more is usually a patched one. Joint compound and spackle are far more porous than painted drywall, and a repair that was not primed pulls the sheen out of the finish coat and shows as a dull patch in side light even when the color matches perfectly.

Spot prime every repair, however small. A quart of primer and ten minutes saves the third coat that a flashing patch would otherwise need across the whole wall.

What this calculator assumes

  • A door is taken as 21 sq ft and a window as 15 sq ft. Deducting them matters on a small room and barely moves a big one.
  • 350 sq ft per gallon is the usual figure on a smooth primed wall. Bare drywall, textured walls and deep color changes all drink more, so drop it to 300 if any of those apply.
  • Ceilings and trim are not included. Run the ceiling as its own area.

Questions people ask

How much paint for a 10x12 room?

About 1.72 gallons for two coats on eight foot walls, so buy two gallons with very little spare.

Why do patched areas look different after painting?

Filler is more porous than the surrounding wall, so it absorbs more paint and dries duller. Spot priming the repair first prevents it.

Do I need to prime a whole wall after repairs?

Usually not. Priming the repairs themselves is enough, as long as every one of them gets covered rather than just the large ones.

Different numbers?

The paint calculator takes any dimensions you like and hands back the same list.

Other common sizes