Paint & Finishes Calculators
Gallons and rolls for paint, deck stain, and wallpaper jobs.
Paint Calculator
Gallons of paint needed for a room, minus doors and windows.
Deck Stain Calculator
Gallons of stain for a deck, including railings and coats.
Wallpaper Calculator
Rolls of wallpaper needed for a room or accent wall.
Epoxy Floor Coating Calculator
Gallons of epoxy for a garage or basement floor, by coats.
Coatings are estimated from coverage: the square feet one gallon or one roll will cover, printed right on the can or label. These calculators compute your real surface area, subtract standard allowances for doors and windows, multiply by coats, and divide by the coverage rate, which you can adjust to match the exact product you are buying.
The main source of error in finish estimating is the surface, not the math. Bare drywall, weathered decking, and heavy texture all absorb more product than the label's smooth-surface rating assumes, so each calculator's notes tell you when to lower the coverage number. Buying the right amount the first time also keeps your whole job in one batch or dye lot, which matters for color consistency.