Paint Calculator
Calculate exactly how much paint you need for your room. Get accurate estimates for walls and ceilings with just a few measurements.
Room Dimensions
Standard ceiling height is 8 ft
Openings
~20 sq ft each
~15 sq ft each
Paint Options
2 coats recommended for best coverage
Your Results Will Appear Here
Enter your room dimensions on the left and click “Calculate” to see how much paint you need.
Top-Rated Paints for Your Project
Hand-picked products to help you get the best results on your project.
BEHR
BEHR Premium Plus 1 Gal. Ultra Pure White Semi-Gloss Interior Paint & Primer
- ✓Paint & primer in one
- ✓Low odor
- ✓Mildew resistant
BEHR Ultra
BEHR Premium Plus Ultra 1 Gal. Eggshell Interior Paint
- ✓Superior coverage
- ✓Stain blocking
- ✓Scuff resistant
Rust-Oleum
Rust-Oleum 1992502 Painter's Touch Latex Paint, Quart, Gloss White
- ✓Quick drying
- ✓Durable finish
- ✓Great for trim & small projects
Wooster
Wooster Brush R975-9 Painter's Choice Roller Kit, 9-Inch
- ✓9-inch roller frame
- ✓Includes paint tray
- ✓Professional quality
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How to Use This Paint Calculator
Step 1: Measure Your Room
Measure the length and width of your room in feet. Don’t worry about being perfectly precise—rounding to the nearest foot is fine.
Step 2: Note the Ceiling Height
Standard ceiling height is 8 feet. If you have higher ceilings, adjust accordingly. Vaulted ceilings? Estimate the average height.
Step 3: Count Doors & Windows
Count all doors and windows in the room. Our calculator automatically subtracts these areas so you don’t overbuy paint.
Step 4: Choose Your Options
Select the number of coats (2 recommended) and whether to include the ceiling. Most projects need 2 coats for proper coverage.
Step 5: Get Your Results
Click Calculate to see exactly how much paint you need, plus a cost estimate to help you budget your project.
Understanding Paint Coverage
What Does “350 sq ft per gallon” Mean?
Paint coverage refers to how much surface area one gallon of paint can cover. Most interior paints cover approximately 350–400 square feet per gallon under ideal conditions.
Factors That Affect Coverage
| Factor | Impact |
|---|---|
| Surface texture | Rough surfaces need more paint |
| Paint color | Dark colors may need extra coats |
| Surface porosity | New drywall absorbs more paint |
| Application method | Spraying uses more than rolling |
Why We Add 10% Extra
Our calculator automatically adds 10% to account for touch-ups and mistakes, uneven application, paint left in tray and roller, and future touch-ups. It’s always better to have a little extra than to run out mid-project!
Pro Tips from Painting Experts
Always Use Primer on New Drywall
New drywall is like a sponge—it absorbs paint unevenly. A coat of primer seals the surface and helps your paint color look consistent.
Buy All Your Paint at Once
Paint colors can vary slightly between batches. Buying all gallons at once ensures consistent color throughout your room.
The "W" Technique
When rolling, paint a large "W" pattern on the wall, then fill it in without lifting the roller. This prevents lap marks and ensures even coverage.
Don’t Skip the Second Coat
Even if the first coat looks good, the second coat adds durability and ensures the color is truly opaque. Wait 2–4 hours between coats.
Save Some for Touch-Ups
Keep at least a quart of paint for future touch-ups. Label the can with the room name and date. Stored properly, latex paint lasts 10+ years.
Frequently Asked Questions
For a standard 12x12 room with 8-foot ceilings, you'll need approximately 1.5–2 gallons of paint for the walls (with 2 coats). If you're also painting the ceiling, add another 0.5 gallon. Our calculator factors in doors, windows, and waste to give you a precise estimate.
Yes! Doors and windows don't need paint, so subtracting them prevents you from buying too much. Our calculator automatically subtracts 20 sq ft per door and 15 sq ft per window from your total wall area.
Most paint jobs require 2 coats for proper coverage and durability. You might get away with 1 coat if: (1) you're using a paint-and-primer combo, (2) painting over a similar color, or (3) using high-quality paint with excellent coverage. When in doubt, plan for 2 coats.
It depends on the room size. One gallon covers about 350–400 sq ft. For a small bedroom (10x10), one gallon might be enough for one coat. For an average bedroom (12x12) with two coats, you'll need about 2 gallons. Use our calculator for an exact estimate based on your room's dimensions.
For vaulted ceilings, estimate the average ceiling height. If your ceiling goes from 8 feet to 12 feet, use 10 feet as your height. This gives you a good approximation. For complex shapes, consider consulting a professional or adding an extra 10–15% to your estimate.
A quart is 1/4 of a gallon. One gallon covers about 350–400 sq ft, while a quart covers about 85–100 sq ft. Quarts are great for small projects like accent walls, touch-ups, or trim. For full rooms, gallons are more economical.