Painting Cost Calculator
- Best for
- Homeowners · Renters (with permission) · DIY painters · Small contractors
- When to use
- Before you buy paint or ask a painter for a quote, so you know roughly how many gallons and dollars a room takes.
How this calculator works
It measures the paintable surface, works out how many gallons that needs for the number of coats you chose, and prices materials and labor separately so you can see where the money goes.
| Step | Formula |
|---|---|
| Wall area | 2 × (length + width) × height − (doors × 21 sq ft) − (windows × 15 sq ft) |
| Ceiling (optional) | length × width |
| Paint gallons | area × coats ÷ coverage, rounded up to whole gallons |
| Primer gallons (optional) | area ÷ coverage, rounded up |
| Materials | paint gallons × paint price + primer gallons × primer price + supplies |
| Labor | paintable area × labor rate (rate is per square foot of surface, not per coat) |
| Range | total ± the spread you pick |
Assumptions you should know
- A standard interior door is treated as about 3 × 7 ft (21 sq ft) and a window as about 3 × 5 ft (15 sq ft). Change the counts if yours are much bigger or smaller.
- Coverage per gallon varies by product and surface. Many labels list a range in the low-to-mid hundreds of square feet per gallon; rough, porous or dark-to-light color changes use more. Use the number printed on your can.
- The default prices ($40 paint, $25 primer, $2 per sq ft labor) are illustrative placeholders, not survey data. Painters may price by the room, the hour or the square foot, and rates differ a lot by area.
- Prep work such as patching drywall, removing wallpaper, moving furniture or painting trim is not included unless you build it into the labor rate or supplies.
Tip: When you ask painters for quotes, mention the square footage this tool gives you and ask whether trim, ceilings and wall repair are included. It makes bids much easier to compare.
Frequently Asked Questions
How much paint do I need for a room?
Divide the paintable wall area by the coverage on your paint can (often listed per gallon) and multiply by the number of coats. This calculator does that and rounds up to whole gallons.
Why does the calculator show a range?
Real jobs vary with wall condition, prep work and local labor rates, so the result is shown as a range around the mid estimate instead of a single number.
Are the default prices real market prices?
No. The defaults are illustrative placeholders. Replace them with prices from your local store and written quotes for an estimate that fits your area.
Your Next Helpful Step
CalculatorHome Repair Budget CalculatorAdd line items, a contingency and see a monthly savings goal.Free templateHome Repair Estimate TemplateLine items, labor, materials, tax and terms. PDF + Excel.GuideHow to Compare Contractor EstimatesLine up scope, materials, license, insurance and payment terms.