How much paint do I need for trim and doors?
One standard interior door takes 1 qt to cover both faces and the edges with two coats. The trim around it uses a different measure: linear feet. A 12x12 room with one door and two windows has about 86 linear feet of baseboard and casing, which takes 2 qt for two coats.
How much paint does one door take?
A standard 30 by 80 inch interior door has about 40 sq ft across both faces and its edges. Two coats make 80 sq ft of spreading. Divide by 350 sq ft per gallon and the exact need is 0.23 gallons, so buy 1 qt. The table assumes smooth doors. Deep panels or louvered doors need more.
| Doors | Painted area | Exact for two coats | Buy |
|---|---|---|---|
| 1 | 40 sq ft | 0.23 gal | 1 qt |
| 2 | 80 sq ft | 0.46 gal | 2 qt |
| 3 | 120 sq ft | 0.69 gal | 1 gal |
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How the math works
Baseboard is the room's perimeter minus the door openings: a 12x12 room is a 48 ft perimeter, and one 3 ft door opening leaves 45 ft of baseboard. Casing is the trim that frames each opening, about 17 ft around a door and 12 ft around a window (two jambs, the head, and the door's own trim). One door and two windows adds 41 ft of casing, so the room totals 86 linear feet of trim.
Then length becomes gallons. A quart of enamel covers roughly 125 linear feet of trim per coat, which is 500 feet to the gallon. Two coats on 86 ft is 0.34 gallons, so 2 qt. Trim eats less paint than people fear; the time is in the taping and the careful brushwork, not the can.
Questions people ask
How much paint does it take to paint one door?
A standard interior door needs one quart for two coats on both faces and the edges. That is about 40 sq ft of surface, or 0.23 gallons at 350 sq ft per gallon. Three doors cross the point where a gallon costs less than three separate quarts.
How much paint do I need for trim and baseboards?
For a 12x12 room with one door and two windows, about 86 linear feet of trim, and two coats of enamel is 2 qt. Trim paint goes by the running foot: a quart brushes roughly 125 linear feet a coat, so a whole small room of baseboard and casing is a quart or two, not a gallon.
How many coats does trim need?
Two, almost always. Trim enamel is glossy and unforgiving, so one coat shows brush lines and lets the old color ghost through, especially white over stained wood. Prime bare or previously stained trim first, then two thin coats of enamel. A same-color touch-up is the only honest one-coat job.
How do I figure the linear feet of trim?
Baseboard is the room perimeter minus the door openings, about 3 ft knocked off per door. Casing is the trim wrapping each opening: count about 17 ft around a door and 12 ft around a window. Add crown or a chair rail as extra perimeter if you are painting those too. The calculator adds it up from your room size and opening counts.
Can I use wall paint on the trim?
You can, but it stays soft and scuffs. Trim takes knocks, so it wants a harder film: an enamel or a urethane-modified alkyd that levels out brush marks and wipes clean. Wall paint in a satin sheen is a passable budget move on closet shelves, not on baseboard a vacuum hits weekly.
Related
Painting the walls of the same room: room paint calculator (its trim toggle covers a quick estimate; this page is the detailed one). Cabinet doors take the same enamel: cabinet paint calculator. One coat or two: the coats guide.