Paint Calculator
Figure out exactly how much paint you need for your next project. Enter your room dimensions, and we'll account for doors, windows, and coats to give you an accurate estimate.
Paint Calculation Formulas
Wall Area
Paintable Area
Gallons Needed
How Paint Coverage Works
Most interior paints cover about 350-400 square feet per gallon on smooth walls. We use 350 sq ft in our calculations to be on the safe side, since real-world coverage depends on wall texture, paint color, and whether you're covering a dark color with a lighter one.
A standard interior door takes up about 21 square feet (3 ft x 7 ft), and an average window is about 15 square feet (3 ft x 5 ft). We subtract these from your wall area since you won't be painting over them.
Accurate Estimates
Accounts for doors, windows, and number of coats
Cost Calculator
Add your paint price to get a total cost estimate
Any Room Size
Works for bedrooms, living rooms, offices, and more
Paint Coverage by Type
Different types of paint have different coverage rates. Here's what to expect from each.
| Paint Type | Coverage (sq ft/gal) | Best For | Dry Time |
|---|---|---|---|
| Flat/Matte | 350-400 | Ceilings, low-traffic rooms | 1-2 hours |
| Eggshell | 350-400 | Living rooms, bedrooms | 1-2 hours |
| Satin | 350-400 | Kitchens, bathrooms, hallways | 1-2 hours |
| Semi-Gloss | 350-400 | Trim, doors, cabinets | 2-4 hours |
| High-Gloss | 300-350 | Trim, furniture, accents | 2-4 hours |
| Primer | 200-300 | New drywall, color changes | 1-3 hours |
Painting Tips for Better Results
Prep Is Half the Job
Clean walls with a damp cloth, fill holes with spackle, and sand rough spots. Good prep work is the difference between a paint job that looks professional and one that doesn't.
Use Quality Painter's Tape
Cheap tape bleeds. Invest in good painter's tape (like FrogTape) and press down the edges firmly. Remove it while the paint is still slightly tacky for the cleanest lines.
Cut In Before Rolling
Use a brush to paint around edges, corners, and trim first (called 'cutting in'). Then use a roller for the large flat areas while the cut-in paint is still wet. This prevents lap marks.
Roll in a 'W' Pattern
Start by rolling paint in a 'W' shape on the wall, then fill it in without lifting the roller. This distributes paint more evenly and prevents streaks.
Frequently Asked Questions
How many coats of paint do I need?
Two coats is the standard for most painting projects. You might get away with one coat if you're painting the same color over a similar shade and using a high-quality paint with good coverage. You'll likely need three coats when going from a very dark color to a very light one, or when using a bright red, yellow, or orange.
Is it cheaper to buy paint in 5-gallon buckets?
Yes, usually by about 10-20% per gallon. If you need more than 3 gallons of the same color, a 5-gallon bucket is almost always the better deal. Plus, all the paint will be perfectly color-matched since it comes from one batch. Just make sure you'll actually use it all.
Should I use primer before painting?
You should use primer when: painting new drywall, covering stains or water marks, making a dramatic color change (like dark to light), or painting over a glossy surface. For repainting a similar color on already-painted walls, a paint-and-primer combo is usually fine.
How long should I wait between coats?
For latex (water-based) paint, wait at least 2-4 hours between coats. For oil-based paint, wait 24 hours. The paint should feel dry to the touch and not tacky at all. High humidity and cool temperatures can extend drying times, so on a damp day, give it extra time.
How much extra paint should I buy beyond the calculator's estimate?
We recommend buying about 10-15% more than what's calculated. Textured walls absorb more paint, some always gets left on the roller or in the tray, and you'll want a small amount for future touch-ups. Store leftover paint in a cool, dry place with the lid sealed tight.
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