Finishing
Paint Coverage Calculator
Stop guessing in the paint aisle. Enter your wall dimensions to find out exactly how many gallons (or liters) of paint or stain you need to buy for a perfect finish.
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Estimating Paint Like a Pro
Buying too much paint wastes money, but running out halfway through a wall is a nightmare. Here are the golden rules of paint estimating:
Always Plan for Two Coats
Even if you buy expensive "One-Coat" paint, you almost always need a second coat for true color accuracy and a durable finish. The only exception is if you are just doing a touch-up over the exact same color.
Subtract the Voids
Don't forget to subtract doors, windows, and large built-in cabinets! A single standard door accounts for 21 square feet. If you are painting a living room with three windows and two doors, that's nearly 90 sq. ft. of space you aren't painting!
The Math Behind Paint Coverage
Estimating paint is simply a matter of calculating the total surface area and dividing it by the coverage rate of your chosen paint (usually found on the back of the can).
| Calculation | Formula | Notes |
|---|---|---|
| Gross Area | Length × Height | Calculated for every wall and added together to get the total surface area of the room. |
| Net Paintable Area | Gross Area − Voids Area | Subtract the square footage of any doors, windows, and unpainted trim. |
| Total Area to Paint | Net Area × Coats | If you are doing two coats, you must double your net paintable area. |
| Paint Needed | Total Area ÷ Coverage Rate | A standard gallon of high-quality interior latex paint covers roughly 350-400 sq ft32-37 sq meters. |
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Frequently Asked Questions
How much does one gallon of paint cover?
A standard gallon of interior wall paint typically covers about 350 to 400 square feet32 to 37 square meters for a single coat. Primer or stain usually covers slightly less, around 300 square feet28 square meters.
How many coats of paint do I need?
You almost always need two coats of paint for a durable, even finish, especially if changing colors. If you are painting raw drywall, you will need one coat of primer and two coats of paint.
Should I subtract doors and windows from my paint estimate?
Yes! A standard door is about 21 square feet2 square meters, and a standard window is about 15 square feet1.4 square meters. If a room has multiple doors and windows, subtracting them can save you from buying an extra gallon of paint.
Does textured drywall require more paint?
Yes. Heavy textures like knockdown or popcorn increase the actual surface area of the wall. You should expect about 10-20% less coverage per gallon on highly textured surfaces compared to smooth drywall.
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