Small Bathroom Paint Calculator
Estimate the paint a small bathroom needs, with the door, a window, and two coats accounted for.
Calculator
Free, runs entirely in your browser, and your numbers never leave your device. Results are estimates for planning only.
What this calculator does
Small bathrooms have a surprising amount of wall, broken up by a door, a window, and fixtures, so it is easy to overbuy. This tool measures the wall area of a compact bathroom, subtracts the door and window, applies two coats, and returns the paint in gallons and liters — usually a quart or two.
How to use it
- Measure the room length, width, and wall height and enter them.
- Set one door and the number of small windows.
- Keep two coats for a steamy room and use a bathroom-rated paint's coverage figure.
- Read the gallons — compact baths often need only a quart or two.
The formula
Paintable = 2 × (length + width) × height − openings. Paint = paintable × coats × (1 + waste%) ÷ coverage.
Example calculation
A 5 ft × 8 ft bathroom with 8 ft walls, one door, one window, two coats at 350 sq ft/gal:
- Wall area: 2 × (5 + 8) × 8 = 208 sq ft
- Openings: 21 + 15 = 36 sq ft
- Paintable: 208 − 36 = 172 sq ft
- Two coats: 172 × 2 = 344 sq ft
- With 10% waste: about 378 sq ft → 378 ÷ 350 ≈ 1.08 gallons
Result: About 1.1 gallons — a single gallon, or two quarts, usually covers it.
Buying and planning tips
- Use a paint rated for kitchens and baths; it resists moisture and mildew.
- Cut in around the tub, mirror, and trim first — a small room is mostly edges.
- Buying quarts instead of a full gallon can save money and storage space.
Common mistakes to avoid
- Buying a full gallon per coat when a small bath needs far less.
- Skipping moisture-resistant paint in a room that sees daily steam.
- Forgetting that tile and the vanity cut the paintable wall down further.
Assumptions and limits
- Each door is treated as 21 sq ft and each window as 15 sq ft.
- Tiled areas and the vanity are not auto-subtracted — lower the wall height or area if a lot is tiled.
- Coverage of ~350 sq ft per gallon is approximate; bare or patched walls cover less.
Frequently asked questions
How much paint do I need for a small bathroom?
A typical 5×8 ft bathroom with 8 ft walls needs roughly one gallon for two coats after subtracting the door and a window — often less, so two quarts can be enough.
Do I need special paint for a bathroom?
A paint labeled for kitchens and baths, or a mildew-resistant satin or semi-gloss, holds up far better against moisture than a flat wall paint.
Should I subtract the tile and vanity area?
Yes, roughly. The calculator only subtracts doors and windows, so reduce the wall height or area you enter if a backsplash, wainscot, or large vanity covers part of the wall.
Is one coat enough in a bathroom?
Two coats give a more even, washable, moisture-resistant finish. One coat may do when repainting a very similar color over a sound surface.
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