Paint Calculator
Work out how many gallons of paint you need for walls and ceilings, with doors, windows and coats included. Then download or print a clean summary for your estimate.
- Walls & ceilings
- Doors & windows deducted
- PDF summary
Your room
Enter one room. For several identical rooms, set "How many rooms".
Prep usually takes as long as painting. Price your crew's time with the employee cost calculator.
Your paint
Updates as you type. Rounded up to the nearest quart.
How to Calculate How Much Paint You Need
Paint is bought by the gallon but used by area. To estimate it, work out the paintable area of the walls (and ceiling, if you're painting it), multiply by the number of coats, and divide by the coverage printed on the paint label. The calculator above does this for you; here is the math behind it.
Paint Calculation Formulas
A standard door is roughly 21 sq ft (3 × 7 ft) and an average window about 15 sq ft. Ceiling area is simply length × width.
Worked Example: a 12 × 14 ft Bedroom
A 12 × 14 ft bedroom with 8 ft walls, one door and two windows, two coats on the walls, one coat on the ceiling, and paint that covers 350 sq ft per gallon:
Rounding up to the nearest quart avoids a second trip to the store, and leaves a little for touch-ups. If the room needs primer, calculate it separately the same way.
Tips for Accurate Paint Estimates
- Use the label's coverage, and the lower end of its range. Rough, porous or unprimed surfaces drink more paint.
- Count coats separately for walls and ceilings, since they often use different paint.
- Add primer for new drywall, stains, patches and big color changes.
- Buy one batch. Color can vary slightly between batches, so buy everything you need at once.
- Price the labor, not just the paint. On most repaints, paint is a small share of the job. Prep, cutting in, rolling and cleanup are where the hours go.
From Gallons to a Profitable Painting Quote
The paint quantity is the easy part. A painting estimate that makes money also covers prep (patching, caulking, masking, moving furniture), labor by task, sundries like tape and plastic, equipment, overhead and profit:
- Price labor at its true cost with the employee cost calculator
- Set your price with the markup calculator or margin calculator
- Send it as a professional quote with painting estimating software