Deck Stain Calculator
Deck stain in gallons or liters with can counts.
What it does
Deck stain buys by coverage: floor area times coats divided by square feet per gallon. Rails, steps, and thirsty grain sit on top, so this page sizes the flat floor and rounds cans up.
The default is a 400 sq ft deck with 1 coat at 250 per gallon. That needs 1.6 gal, or 2 gallon cans. Metric defaults convert the same deck to 37.2 m2 and give 6.1 L in 2 cans of 4 L.
Coverage is the judgment input. New smooth boards stretch past 250, while weathered gray boards soak well below it. Power wash, brighten, and dry before opening a can, since stain over dirt peels by spring.
Unlike fence pickets that stand vertical, decks wear flat under sun and feet. Expect recoat cycles near 2 to 3 years for transparent stains on sunny exposures.
How to use
- Pick imperial or metric first.
- Enter deck floor area.
- Enter coat count.
- Read stain first, then cans and area.
- Measure rails extra on site.
Formula
- area
- Deck floor area in the active units.
- coats
- Coat count, often 1 for stain.
- 250
- Planning coverage per gallon.
Coverage of 250 sq ft per gallon is a planning rate for average deck boards; thirsty, rough, or weathered wood falls below it while smooth sealed wood beats it. Rails and balusters add area past the footprint and need measuring. Metric converts 250 sq ft per gal to 6.14 m2 per L.
Worked example
Example: 400 sq ft deck
400 sq ft deck, 1 coat at 250 sq ft per gal (metric 37.2 m2).
- Need: 400 x 1 / 250 = 1.6 gal.
- Cans: ceil(1.6) = 2 cans (1 gal).
- Metric: 37.2 / 6.14 = 6.1 L.
- Metric cans: 6.1 / 4 = 1.53, up to 2 cans.
- Tool shows 1.6 gal imperial and 6.1 L metric.
Reference table
| Deck | Gallons | Cans |
|---|---|---|
| 200 sq ft | 0.8 gal | 1 |
| 300 sq ft | 1.2 gal | 2 |
| 400 sq ft | 1.6 gal | 2 |
| 500 sq ft | 2 gal | 2 |
| 600 sq ft | 2.4 gal | 3 |
Limits
- Flat floor only. Rails and steps extra.
- One coverage rate. Thirsty wood needs more.
- Ignores cleaner, prep, and tools.
- Recoat timing excluded.
Common mistakes
- Measuring footprint without rails.
- Using paint coverage for stain.
- Rounding cans down.
- Staining damp or dirty boards.
- Skipping the second coat math.
Try it yourself
Quick checks. Answers sit tucked under each question.
600 sq ft, 1 coat?
2.4 gal (600 / 250), 3 cans.
400 sq ft, 2 coats?
3.2 gal (400 x 2 / 250), 4 cans.
Questions
How much stain?
Area times coats over 250 sq ft per gal. Here 1.6 gal.
How many cans?
Gallons rounded up. Here 2 cans.
What is that in metric?
6.1 L in 2 cans (4 L) for 37.2 m2.
Why did I run short?
Rails, steps, and thirsty wood drink more. This page covers flat area only.
Does it work in metric?
Yes. Enter m2 for liters and 4 L cans.
Prep included?
No. Cleaner, brightener, and sandpaper sit outside stain math.