Trim and baseboard paint calculator
Trim is mostly length, so this calculator works in linear feet: baseboards, door and window casings, door jambs and crown, turned into square feet and then quarts.
Enter your measurements
More options: Casing · Jamb · Crown …
- 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
Baseboard: 2 × (12 ft + 12 ft) − 1 × 3 ft doorway = 45 ft × 4 in = 15 sq ft
Doors: 1 × (casing 3.5 sq ft + jamb 6.1 sq ft)
Windows: 2 × casing 3.5 sq ft
31.6 sq ft × 2 coats ÷ 350 sq ft/gal × 1.1 extra = 0.8 qt → 1 quart
- 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.
Quick answers for common sizes
| Example | Answer |
|---|---|
| How much trim paint for one room | 0.8 qt: buy 1 quart |
| How much paint for baseboards | 1.1 qt per 100 ft of 5¼ in base: buy 2 quarts |
Trim paint by baseboard height (same room and casings)
| Baseboard height | Trim surface (one coat) | Trim paint needed | Buy (gallons and quarts) |
|---|---|---|---|
| 3.25 in | 28.8 sq ft | 0.72 qt | 1 quart |
| 4 in | 31.6 sq ft | 0.8 qt | 1 quart |
| 5.25 in | 36.3 sq ft | 0.91 qt | 1 quart |
| 7.25 in | 43.8 sq ft | 1.1 qt | 2 quarts |
Doors are assumed to be 36 × 80 in openings and windows 36 × 60 in; casings run around them at the width you set. Door jambs are included for every door casing. New to this? Paint words explained.
How the trim paint calculator works
baseboard = length × height door casing = (2 × 80 in + 36 in + 2 × casing width) × casing width door jamb = (2 × 80 in + 36 in) × jamb depth window casing = (2 × (36 + 60) in + 4 × casing width) × casing width paint = total × coats ÷ coverage
Trim takes surprisingly little paint. The baseboards, one door and two windows of a 12 × 12 room come to about 32 sq ft; two coats at 350 sq ft per gallon is under a quart. That job is on how much trim paint for one room. The baseboards of a whole floor, a few hundred linear feet, still come in under a gallon: see how much paint for baseboards.
Which paint for trim
- Sheen. Semi-gloss is the usual trim sheen because it wipes clean and stands up to shoes and vacuum cleaners. Satin is softer-looking; high gloss shows every brush mark and dent. See the paint sheen chart.
- Enamel. Waterborne alkyd and urethane enamels level out to a smoother, harder finish than wall paint. Benjamin Moore Advance, for example, lists 400–500 sq ft per gallon.
- Coverage. Trim enamels list similar coverage to wall paints (350–400 on the ProMar 200 semi-gloss sheet), but you brush them, and brushing on narrow trim wastes a little more.
Tips
- Caulk the gaps between trim and wall before painting: how many feet of caulk in a tube.
- Paint trim last, after walls, and cut in onto the wall slightly; or paint trim first and tape it off before the walls. Either works, but pick one.
- Previously painted glossy trim needs a scuff-sand so the new coat grips; oil-based trim under latex needs a bonding primer.
- Exterior trim (fascia, window trim, corner boards) uses the same math: measure the length and face width and add it here.
What you’ll need
- Angled sash brush (2–2½ in)Budget price
For cutting in along ceilings, corners and trim. A nylon-polyester brush is what the latex data sheets recommend.
See options on Amazon (opens in a new tab) - Paintable acrylic latex caulkBudget price
For trim gaps and baseboard joints before painting. Check the tube for its paint-ready time.
See options on Amazon (opens in a new tab) - Painter’s tape (multi-surface)Budget price
Masks trim, ceilings and glass. Pull it at an angle while the last coat is still slightly soft for the cleanest line.
See options on Amazon (opens in a new tab) - Sanding sponges (fine/medium)Budget price
Knocks down patches and scuffs glossy trim so the next coat grips. Damp sponges keep dust down.
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 trim paint do I need for one room?
Usually one quart. A 12 × 12 room with 45 ft of 4 in baseboard, one door and two windows has about 32 sq ft of trim; two coats with 10% for brushing take about 0.2 gallons. See how much trim paint for one room.
How much paint for baseboards?
With two coats at 350 sq ft per gallon and 10% for brushing, a quart paints about 90 linear ft of 5¼ in baseboard, or about 120 ft of 4 in. See how much paint for baseboards.
What sheen should trim be?
Semi-gloss is the common choice for durability and easy cleaning; satin for a softer look.
Do I include the doors in the trim?
Only the casings and jambs. The door slabs are a separate, bigger area: the door paint calculator does both sides and the edges.
Related guides
Sources
- Sherwin-Williams, ProMar 200 Zero VOC Interior Latex Semi-Gloss (B31 series), product data sheet (opens in a new tab) — Coverage 350–400 sq ft per gallon at 4 mils wet; for walls, ceilings and trim.
- Benjamin Moore, Advance Interior Matte (791), technical data sheet (opens in a new tab) — Coverage 400–500 sq ft per gallon at 3.6 mils wet; a cabinet, door and trim enamel; matte 2–6 units at 85°.