Paint Coverage Calculator

Planning a DIY room makeover? Our Paint Coverage Calculator helps you figure out exactly how many gallons of paint you need before you head to the hardware store.

How We Calculate Paint Coverage

The industry standard rule of thumb is that 1 gallon of paint covers approximately 400 square feet of smooth, interior wall space for a single coat.

To find your total paintable area, we use the following process:

1. Calculate Total Wall Area: $\text{Area} = 2 \times (\text{Length} + \text{Width}) \times \text{Height}$
2. Subtract Obstacles: We subtract standard area deductions for every door (approx. $21\text{ sq ft}$) and window (approx. $15\text{ sq ft}$) in the room.
3. Multiply by Coats: The final area is multiplied by the number of coats you plan to apply. Darker colors or unprimed drywall typically require at least two coats.

Tips for a Successful Paint Job

Buy a Little Extra

While the math is precise, drywall textures, thick rollers, and accidental spills happen. It's always best to buy slightly more paint than the exact calculation requires so you have enough for touch-ups later.

Don't Forget the Ceiling!

If you plan to paint the ceiling, you will need to add the square footage of the ceiling $(\text{Length} \times \text{Width})$ to your total. Ceiling paint is often sold separately since it is formulated to drip less.