How to use the paint cost calculator
- Enter the room dimensions, doors and windows.
- Enter coats and the coverage on the can.
- Enter your paint price and supplies budget.
- Adjust the professional rate to local quotes.
Formula
DIY = ⌈wall area × coats ÷ coverage⌉ × price per gallon + supplies. Professional = floor area × rate per sq ft.
Worked example
A 12 × 12 ft room: 349 sq ft of wall, 2 coats → 2 gallons; at $40/gal plus $30 supplies, $110 DIY. A pro at $2.75–$4.69 per sq ft of floor: $396–$675.
Tips for using the paint cost calculator
- Include primer, patching compound, tape and rollers in a DIY budget, not just paint.
- Professional prices rise with high ceilings, heavy repairs and many trim colors.
- Homes built before 1978 may have lead paint; that changes how prep must be done.

Paint Cost Calculator FAQs
How much does it cost to paint a room?
At typical rates of about $2.75–$4.69 per sq ft of floor, a 12 × 12 ft room is roughly $400–$675 professionally; DIY materials are usually a fraction of that.
Why is the pro rate based on floor area?
Many painters quote interior rooms by floor square footage as a shorthand. Others quote by wall area, by room, or by the hour — compare like with like.
What about lead paint?
In pre-1978 homes, contractors must follow the EPA RRP rule when disturbing painted surfaces, which can add cost.
