Painting Estimate Calculator
Enter room size, openings, coats and your own rates to get paintable area, gallons, labor hours and a suggested price for an interior room.
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This painting estimate calculator works out an interior room the way most painters do it on the back of a work order: wall area minus doors and windows, plus the ceiling if you're doing it, times coats. From there it gives you gallons, labor hours at your production rate, materials and labor cost, and a suggested price with your markup on top. Run it room by room and add the rooms up for a whole-house number. For software that builds these estimates into quotes and schedules, see our painting software guide.
Interior painting estimate
Results
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How to use this calculator
- Room size. Enter the room's length and width in feet and the wall height. For an L-shaped room, split it into two rectangles and run each one.
- Doors and windows. Enter how many of each. The calculator takes 21 sq ft off for each door (a standard 3 x 7 opening) and 15 sq ft for each window.
- Coats. Pick 1, 2 or 3. Two is normal for a repaint. Three is common for big color changes without primer.
- Ceiling. Choose yes to add the ceiling (length × width) to the paintable area.
- Paint coverage and price. Coverage defaults to 350 sq ft per gallon. Enter what you pay per gallon for the product you're quoting.
- Production rate and labor rate. Production defaults to 150 sq ft per labor hour. Enter your loaded labor rate per hour, meaning wages plus payroll taxes and workers' comp, not just the hourly wage.
- Markup. Enter your markup percentage on materials and labor.
The formula
- Wall area = 2 × (length + width) × wall height
- Openings = (doors × 21) + (windows × 15)
- Paintable area = wall area − openings, plus length × width if the ceiling is included
- Gallons = paintable area × coats ÷ 350, rounded up to the next whole gallon
- Labor hours = paintable area × coats ÷ production rate
- Materials cost = gallons × price per gallon
- Labor cost = labor hours × labor rate
- Suggested price = (materials cost + labor cost) × (1 + markup %)
Worked example
Say you're quoting a 12 x 14 bedroom with 8 ft walls, two doors (entry and closet), two windows, two coats, and the ceiling included. You pay a hypothetical $45 a gallon, your loaded labor rate is $55 an hour, and you use a 20% markup.
- Wall area: 2 × (12 + 14) × 8 = 416 sq ft
- Openings: (2 × 21) + (2 × 15) = 72 sq ft
- Walls after openings: 344 sq ft
- Ceiling: 12 × 14 = 168 sq ft
- Paintable area: 512 sq ft
- Coverage needed: 512 × 2 = 1,024 sq ft
- Gallons: 1,024 ÷ 350 = 2.93, rounded up to 3
- Labor hours: 1,024 ÷ 150 = 6.8 hours
- Materials: 3 × $45 = $135
- Labor: 6.83 hours × $55 = about $375
- Suggested price: ($135 + $375.47) × 1.20 = about $613
Run the same room with one coat and no ceiling and the paintable area drops to 344 sq ft, one gallon, and about 2.3 labor hours. That's a useful check when a customer asks why a color refresh costs so much less than a full repaint with ceilings.
A 20% markup here is about a 16.7% gross margin. If your overhead runs higher than that, the price is too low before you've added a single line for trim or prep.
Things the calculator can't see
Prep. Patching nail pops, caulking cracks, sanding glossy surfaces, masking floors and moving furniture can take as long as the painting on an older house. Add prep hours separately.
Trim and doors. Baseboards, casing, crown, window sills and door slabs aren't in the wall area. Most painters price them by linear foot or per door.
Different products. Ceilings usually get flat ceiling paint, and walls get eggshell or satin. The calculator lumps them into one gallon count at one price. If your ceiling paint costs less, split the job into a walls run and a ceiling run.
Surface and color. Fresh drywall, heavy texture and stained or patched walls drink paint and may need primer first. Deep or bright colors may need an extra coat. Real coverage can drop well below 350 sq ft per gallon on rough surfaces.
Second-coat speed. The calculator assumes the same production rate for every coat. Second coats usually go faster because cutting lines are already set, so on big jobs the labor estimate can run a little high.
Access and height. Stairwells, two-story foyers and vaulted ceilings need ladders, planks or scaffolding and slow production down. Adjust the production rate for those rooms.
Sales tax, disposal and travel. Depending on your state, materials may be taxable. Drive time, parking and paint disposal aren't included either.
Questions owners ask
How much paint do I need for a 12x12 room?
A 12 x 12 room with 8 ft walls has 384 sq ft of wall. Take out one door (21 sq ft) and one window (15 sq ft) and you have about 348 sq ft. Two coats is about 696 sq ft of coverage, which at 350 sq ft per gallon rounds up to 2 gallons for the walls. Add the 144 sq ft ceiling and you'll need a third gallon.
How many square feet can a painter do in an hour?
It varies a lot by surface, crew and how much cutting in there is. This calculator defaults to 150 sq ft per labor hour as a starting point for rolling and cutting walls. Track your own crew's hours on a few jobs, divide the square footage by the hours, and replace the default with your real number.
What markup should a painting contractor use?
There's no single right number. It needs to cover overhead (insurance, vehicles, the office, estimating time) and leave profit. Know the difference between markup and margin: a 25% markup on cost gives a 20% gross margin. Work backward from the margin you need, then set the markup in the calculator to match.
Should I charge by the room or by the square foot?
Many painters quote by the job or by the room to customers, but build the number from square footage and hours behind the scenes, which is what this calculator does. Per-room flat prices are easy to sell but get risky when rooms vary in ceiling height, trim and prep. Use the square-foot math to set and check your room prices.
Does the calculator include trim, doors and prep?
No. It covers wall and ceiling area. Baseboards, casings, crown, doors and cabinets are usually priced per linear foot or per piece. Prep work such as patching, caulking, sanding, masking, moving furniture and primer on repairs or strong color changes should be added as separate line items.