Paint Calculator
for Rooms and Ceilings
Enter your room, your openings and your finish. See how many gallons you need for the coats you're planning.
Coverage by finish · Doors and windows taken off · Works on your phone
Estimates only. Your numbers stay in your browser and aren't saved or sent anywhere.
How to calculate paint
Wall area = 2 × (length + width) × height
Paintable area = walls + ceiling − 21 sq ft per door − 15 sq ft per window
Gallons = paintable area × coats × (1 + waste %) ÷ coverage
For example, a 12' by 12' room with 8' ceilings, one door and two windows has 333 sq ft to paint. Two coats of satin with 10% waste comes to 3 gallons.
How far a gallon of paint goes
| Product | Coverage range | Calculator uses |
|---|---|---|
| Flat / matte | 350–400 sq ft | 375 sq ft |
| Eggshell / satin | 300–350 sq ft | 325 sq ft |
| Semi-gloss / gloss | 250–300 sq ft | 275 sq ft |
| Primer | 250–400 sq ft | 325 sq ft |
| Exterior | 250–300 sq ft | 275 sq ft |
Rough or textured surfaces soak up more, and so does new drywall. Check the can, and raise the waste figure for heavy texture.
How many coats do you need?
Plan on two coats for most repaints, and for new drywall after primer. A strong color change can take more, or a tinted primer first. A single coat might do if you're going over the same color and the wall is in good shape.
Which sheen to use where
| Sheen | Best for |
|---|---|
| Flat / matte | Ceilings and low-traffic walls |
| Eggshell | Living rooms and bedrooms |
| Satin | Hallways and kitchens |
| Semi-gloss | Trim, doors and bathrooms |
| Gloss | Cabinets and trim accents |
Questions
- With 8' ceilings, one door and two windows, two coats of satin takes about 3 gallons. Add more if you're painting the ceiling.
- About 250 to 400 sq ft per coat, depending on the finish and the surface. Check the can for your product.
- Yes. The calculator takes off 21 sq ft per door and 15 sq ft per window. If your openings are unusually large, measure them and adjust.
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