A 16×20 ft deck (320 sq ft) needs about 3.2 gallons of stain for two coats at 200 sq ft per gallon — buy 4 gallons. With railing on three sides (52 ft), plan on 7 gallons.
Change the numbers
The calculator below is pre-filled for this project. Adjust any value — including feet and inches — and the results update instantly.
Your results
Stain to buy4 gallons
Exact amount (2 coats)3.2 gal
Deck surface320 sq ft
Railing (both sides, approx.)0 sq ft
Gallons by coverage rate (2 coats)
Coverage
Floor only (exact)
Floor only (buy)
Floor + railing (buy)
150 sq ft/gal
4.27
5
9
200 sq ft/gal
3.2
4
7
250 sq ft/gal
2.56
3
6
300 sq ft/gal
2.13
3
5
Use the 150 sq ft row for rough, weathered or never-sealed wood and the 250–300 rows for smooth, previously sealed boards.
The math
16 × 20 = 320 sq ft × 2 coats ÷ 200 = 3.2 gal
Common questions
How many gallons of stain for a 16x20 deck?
About 3.2 gallons for two coats on the deck floor (buy 4), or 7 gallons including 52 ft of railing.
