Wood Stain & Finish Coverage Calculator

Estimate how many gallons of stain, paint, or finish you need from the surface area and your product's coverage rate (check the can label — coverage varies significantly by product and wood porosity).

Surface Area (sq ft)

Coverage per Gallon (sq ft)

Number of Coats

How the quantity is worked out

Area divided by the rate on the can, once per coat:

gallons per coat = surface area / coverage per gallon
total gallons    = gallons per coat × coats
quarts           = total gallons × 4

The defaults give 600 / 300 = 2.00 gallons a coat, and two coats is 4.00 gallons or 16.0 quarts. The quart line is a straight unit conversion, not a shopping list - buying 16 quarts costs far more than four gallon cans. A coat count below 1 falls back to 1, and a zero area or coverage rate is rejected.

The coverage rate is the whole answer

Everything else here is arithmetic; the rate you type decides the result, and it swings by a factor of two on the same product:

Surface	Typical sq ft per gallon
Sanded hardwood, oil stain	350-400
Smooth planed softwood	250-350
Rough-sawn or weathered timber	150-250
End grain and cut ends	Half the rate of the face

Measure every face that gets finished. Fence pickets and shelves take stain on both sides and all four edges, so a 6" × 6 ft board is closer to 7 sq ft of surface than the 3 sq ft of its front. Deck board edges count too, once the gaps are wide enough to reach.

Coats are treated as identical here, and they are not. Bare wood drinks the first coat, and the second often covers 25-50% further, so this overstates a two-coat job on new timber and understates the first coat on rough stock.

Frequently asked questions

How much stain do I need for a 500 sq ft deck?

Around 2.5 gallons a coat at 200 sq ft per gallon, which is a realistic rate for weathered decking. On a newly laid smooth deck at 300, the same area needs 1.67 gallons.

How many square feet does a gallon of wood stain cover?

Between 150 and 400, depending almost entirely on how thirsty the wood is. Take the number from your own can, then move it toward the low end for anything rough, weathered or unsanded.

Should I buy the exact amount the calculator gives?

Round up to whole cans and add a little. Opening a fresh can mid-wall risks a visible colour break between batches, and running a pint short is worse than having a pint left.