🪣 Deck Stain Calculator
Estimate how many gallons of stain you need to finish your deck, based on its size, the number of coats, and your stain’s coverage rate.
What this calculator does
The deck stain calculator estimates how many gallons of stain you need to finish a deck, accounting for its size and how many coats you plan to apply.
The formula
Deck area in square feet is length multiplied by width. That figure is multiplied by the number of coats you plan to apply, since each coat covers the whole surface again, and then divided by the product’s coverage rate (printed on the can, typically 150 to 300 square feet per gallon depending on wood porosity and stain type).
Rough-sawn or weathered wood soaks up more stain than smooth, new lumber, so actual coverage can vary. It’s a good idea to round up and keep the leftover for future touch-ups.