Deck Stain Calculator
Gallons of stain for deck boards, rails and stairs.
Enter your values
Enter the deck length in ft.
Enter the deck width in ft.
Enter the railing length in ft.
Enter the number of steps you are working with.
Enter the coats you are working with.
Enter the coverage per gallon in sq ft.
Enter the price per gallon in $.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Stain needed
- 3.39 gallons
- Buy
- 4 gallons
- Total stainable area
- 424 sq ft
- Deck surface
- 192 sq ft
- Railings + stairs
- 232 sq ft
- Cost
- $180.00
Working
- 1424 ft2 x 2 coats / 250 = 3.39 gal
Quick answer
Gallons = total stainable area x coats divided by coverage per gallon. Rails and balusters add a surprising amount of area.
gallons = (deck + rail + stair area) x coats / coverage
At a glance
| What it does | Gallons of stain for deck boards, rails and stairs. |
|---|---|
| Category | Home & DIY |
| Inputs needed | Deck length, Deck width, Railing length, Number of steps, Coats, Coverage per gallon, Price per gallon |
| Main output | Stain needed |
| Formula | gallons = (deck + rail + stair area) x coats / coverage |
| Cost | Free — no sign-up, no download |
How to use the Deck Stain Calculator
- 1Measure the deck surface, then the total run of railing.
- 2Railings need roughly four times their length in square feet once you count both sides and the balusters.
- 3Check the coverage on the can - semi-transparent stains go further than solid.
Inputs explained
- Deck length(ft)
- Enter the deck length in ft.
- Deck width(ft)
- Enter the deck width in ft.
- Railing length(ft)
- Enter the railing length in ft.
- Number of steps
- Enter the number of steps you are working with.
- Coats
- Enter the coats you are working with.
- Coverage per gallon(sq ft)
- Enter the coverage per gallon in sq ft.
- Price per gallon($)
- Enter the price per gallon in $.
Worked example
Using the values the calculator loads with:
Inputs
- Deck length16 ft
- Deck width12 ft
- Railing length40 ft
- Number of steps4
- Coats2
- Coverage per gallon250 sq ft
- Price per gallon45 $
Results
- Stain needed3.39 gallons
- Buy4 gallons
- Total stainable area424 sq ft
- Deck surface192 sq ft
- Railings + stairs232 sq ft
- Cost$180.00
- 424 ft2 x 2 coats / 250 = 3.39 gal
Frequently asked questions
How many coats of deck stain?
Two for semi-transparent and solid stains on bare wood, one maintenance coat afterwards. Never apply more than the wood can absorb or it will peel.
When can I stain new pressure-treated wood?
Wait until it absorbs water rather than beading it - typically a few weeks to several months depending on climate.
What do I need to enter into the Deck Stain Calculator?
Just 7 values: deck length, deck width, railing length, number of steps, coats, coverage per gallon, price per gallon. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Deck Stain Calculator work out the answer?
Gallons = total stainable area x coats divided by coverage per gallon. Rails and balusters add a surprising amount of area. It applies the formula gallons = (deck + rail + stair area) x coats / coverage and shows the working so you can check each step by hand.
Is the Deck Stain Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.