How to measure a room for paint
For walls, measure the perimeter of the room and multiply by the ceiling height. A 14 × 16 ft room with 9 ft ceilings has a perimeter of 60 ft, so 540 sq ft of wall. Subtract large openings (a standard door is about 20 sq ft, a window about 15) if you want to be precise; many painters leave them in to cover cutting-in time.
Ceilings are length times width. Trim is measured in linear feet, and doors and windows are usually counted and priced each.
For gallons, divide the area by the coverage on the can, often around 350–400 sq ft per gallon per coat, and multiply by the number of coats. Rough or porous surfaces drink more, so round up.
Per square foot, per room or per hour
| Method | Good for | Watch out for |
|---|---|---|
| Per square foot | Larger jobs, exteriors, new construction | Clients comparing your rate with a lower one that excludes prep |
| Per room | Standard bedrooms and repaints | Oversized rooms, vaulted ceilings, heavy color changes |
| Per hour | Small touch-ups, odd jobs | Clients who can't predict the total |
Mixing is fine. The example above prices the big living room by the square foot and the bedroom as a flat room price, because that's how the painter knows those spaces.
Prep, coats and the things that change the price
Prep is where painting estimates go wrong. Spell out what's included:
- Patching: nail holes and hairline cracks, or real drywall repair?
- Primer: needed over stains, new drywall, or a big jump from dark to light.
- Number of coats: two is standard; saturated reds and yellows can need three.
- Caulking gaps in trim before painting.
- Furniture and protection: who moves it, and covering floors.
For exterior work, add pressure washing, scraping and sanding, and any wood replacement as an allowance, since rot often hides under old paint. Also mention lead-safe practices if the home was built before 1978; renovation work disturbing painted surfaces in those homes is covered by EPA lead rules.
Exclusions and terms
Write down what's out: wallpaper removal, cabinet painting, moving heavy furniture, ceiling repairs. Say who buys the paint and whether the price includes it; some clients like to choose a brand, and a separate paint line makes that easy to swap.
Set a validity date so last spring's price doesn't come back to you in the fall, and agree on a deposit before you book the dates. When the job is done, the matching painting invoice can be created from this estimate.
Exterior estimates: extra lines to remember
Outside work adds steps that interior estimates don't have: ladder or lift rental for second stories, masking windows and fixtures, and weather days that push your schedule. Price siding by square foot of wall area, trim and fascia by linear foot, and shutters or doors per piece. A note that the start date depends on dry weather above a minimum temperature saves a lot of phone calls.
Last checked October 23, 2026.