Easy Paint Calc

How much trim paint for one room?

Short answer

The baseboards, one door casing and two window casings in a 12 × 12 ft room add up to about 31.6 square feet and need 0.8 quarts of trim paint for two coats. Buy 1 quart.

How to work it out

  1. Baseboard: 2 × (12 ft + 12 ft) − 1 × 3 ft doorway = 45 ft × 4 in = 15 sq ft
  2. Doors: 1 × (casing 3.5 sq ft + jamb 6.1 sq ft)
  3. Windows: 2 × casing 3.5 sq ft
  4. 31.6 sq ft × 2 coats ÷ 350 sq ft/gal × 1.1 extra = 0.8 qt → 1 quart

Trim is the smallest paint order in a room and the easiest to overbuy. In a typical bedroom the baseboards, one door and two windows add up to roughly 32 sq ft, and two coats of enamel come to well under a quart.

Adjust for your project

ft
ft
Each door takes 3 ft off the baseboard
in
Face height; add ½ in (12 mm) for the top edge on thick profiles
Count both sides of a doorway if you paint both rooms. Jambs are added for each
Two coats for a durable, even trim finish
sq ft/gal
Trim enamels: Sherwin-Williams ProMar 200 semi-gloss lists 350–400 sq ft/gal; Benjamin Moore Advance 400–500
More options: Casing · Jamb · Crown …
in
in
The inside face of the door frame: about 4½ in in a 2×4 wall
ft
in
%
10% covers what stays in the brush and on the edges; 15–20% for ornate profiles
Buy (gallons and quarts)1 quart
Trim paint needed
0.8 qt (0.75 L)
Cans of the size you chose
1 can · 1-quart
Trim surface (one coat)
31.6 sq ft
Paint per coat
0.36 qt
Coverage used
350 sq ft/gal
Of which baseboards
15 sq ft
Of which casings and jambs
16.6 sq ft
  • Molded profiles have more surface than their flat width; on ornate trim, add 10–20% under Extra.
  • Under a quart: buy a quart. Half-pints and sample cans rarely come in trim enamel.
  • Old house? If it was built before 1978, read lead paint safety before you sand or scrape: EPA advises assuming old paint contains lead until it is tested.

For this job · affiliate link
Angled sash brush (2–2½ in)Trim is brush work. A 2 in angled sash brush lays enamel along a baseboard top edge in one clean pass.
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Trim paint by baseboard height (same room and casings)

Trim paint by baseboard height (same room and casings)
Baseboard heightTrim surface (one coat)Trim paint neededBuy (gallons and quarts)
3.25 in28.8 sq ft0.72 qt1 quart
4 in31.6 sq ft0.8 qt1 quart
5.25 in36.3 sq ft0.91 qt1 quart
7.25 in43.8 sq ft1.1 qt2 quarts

Where the 32 square feet come from

  • Baseboard: 15 sq ft. 45 linear ft (the 48 ft perimeter less a 3 ft doorway) at 4 in high.
  • Door: about 9.7 sq ft. The casing around a 36 × 80 in opening on one side, 3.6 sq ft at 2½ in wide, plus the 4½ in jamb inside the frame, about 6.1 sq ft.
  • Two windows: about 7 sq ft. Casing on all four sides of a 3 × 5 ft window is about 3.5 sq ft each.
  • Two coats: 0.8 quarts with 10% for brush loss. One quart with a little left for touch-ups. Crown molding adds about 0.4 sq ft per linear ft at 4½ in; 48 ft of crown would push the job to a second quart.

If you are painting every room, add them up rather than buying a quart per room: four or five rooms of trim fit in a gallon, and a gallon of trim enamel costs much less per ounce than quarts. The baseboards alone, by the linear foot, are on how much paint for baseboards.

The walls of the same room take about 2 gallons: how much paint for a 12x12 room. The door slab itself is a separate job: how much paint for a door.

Different size? Use the full Trim & Baseboard Paint Calculator.

What you’ll need

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Frequently asked questions

How much trim paint for a room with crown molding?

With 48 ft of 4½ in crown added, about 1.25 quarts for two coats: 2 quarts.

How much paint for trim and doors in one room?

Trim for two doorways and two windows takes about 1.01 quarts; add about a quart for each door slab painted on both sides.

Other common sizes

Sources