CalculynHow it works
One gallon covers about 350 square feet. We subtract roughly 18 sq ft per door or window.
Formula
Gallons = (Wall area × Coats) ÷ 350
Example
A 14×12 ft room with 8 ft walls and two coats needs about 2.25 gallons.
Assumptions & limitations
- Material estimates only — buy 5–10% extra for waste and cuts.
- Check coverage figures on your product label.
Frequently asked questions
Do I need primer?
Use primer on new drywall, stains, or when making a big color change.