Deck Stain Calculator
Enter the deck area, the coats and the coverage on your can to get the gallons and cans of stain, with an optional cost from your own price.
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How to use the Deck Stain Calculator
- Type the “Deck surface area”. You can enter it in ft² or m².
- Set “Coats”. The default is 2, which follows a solid color stain source. One semi-transparent stain page says one coat is enough, so change it if your can says so.
- Set the “Coverage (ft² per gallon, per coat)”. The default is 250. Use the figure on your can if you have it.
- Open “More options” if you need them. Add “Railings, stairs and other area”, choose a “Can size” of 1 or 5 gallons, and type a “Price per can” and sales tax if you want a cost.
- Read the results: “Stain needed”, “Cans to buy”, the liters, “Area to stain”, “Area covered, all coats” and “Left over after the job”.
- Check the cost. It appears only when you have typed a price per can.
- Read any warnings. The tool warns if the total area is under 20 or over 5,000 ft², if coverage is outside 150 to 500, if you enter more than 4 coats, or if the result is a part coat.
The tool also has presets for 144, 256 and 400 ft² decks and for rough wood at 150 ft² per gallon. Pick one as a starting point, then change the numbers to match your deck.
How much stain to apply to a deck?
The tool multiplies the deck area, plus any extra area, by the number of coats, then divides by the coverage. The formula is: stain in gallons = (deck area + extra area) x coats / coverage. The number of cans is that figure divided by the can size, rounded up to the next whole can. For example, 200 ft² with 2 coats at 250 ft² per gallon needs 1.6 gallons, which means two one-gallon cans, 0.4 gallon left over and 400 ft² covered. Liters are calculated with 1 gallon = 3.785411784 L.
Coverage is the number that changes the result most. The published figures differ. One solid color oil decking stain data sheet gives 400 to 500 ft² per gallon on smooth surfaces and 250 to 350 on rougher surfaces. A solid color stain product page gives about 250 to 350. A semi-transparent stain page gives 150 to 400, depending on how porous the wood is. The default of 250 is the lowest value that all three ranges share, which is the overlap of 250 to 350. The full published span is 150 to 500, and the tool warns outside that span. Old or absorbent wood can take more stain on the first coat. Coverage varies by product, so the number on your can is the best guide for your project.
How much does it cost to restain a deck?
The cost is the number of cans multiplied by the price per can you type, multiplied by 1 plus the sales tax percentage. The formula is: cost = cans x price per can x (1 + tax %). The tool does not include a price, so the figure depends only on what you enter. Labor, cleaner and surface prep are not included.
Here is a worked example. A 320 ft² deck with 60 ft² of railing gives 380 ft². With 2 coats at 250 ft² per gallon, that is 3.04 gallons, which needs one 5-gallon can. At a typed price of 180 with 7 % tax, the can costs 192.60.
Sources (checked 15 October 2026): paintsupply.com · olympic.com · thompsonswaterseal.com
Worked examples
| Input | Result |
|---|---|
| 200 ft² deck, 2 coats at 250 ft² per gallon | 1.6 gal, 2 can(s) of 1 gal |
| 144 ft² deck, 1 coats at 300 ft² per gallon | 0.48 gal, 1 can(s) of 1 gal |
| 320 ft² deck, 2 coats at 250 ft² per gallon | 3.04 gal, 1 can(s) of 5 gal |
| 30 m² deck, 2 coats at 350 ft² per gallon | 1.845 gal, 2 can(s) of 1 gal |
Calculated by the tool above; open it with the same values to see each step.
Frequently asked questions
Is the Deck Stain Calculator free to use?
Yes. It runs in your browser, is free and needs no sign-up. Nothing you type is uploaded.
Why does the calculator default to 250 ft² per gallon?
The default is the lowest value shared by the three published coverage ranges, which overlap at 250 to 350. You can change it to any value. The tool warns you if the coverage is outside 150 to 500.
How many coats of deck stain do I need?
It depends on the product. One solid color stain page says two coats are needed. A semi-transparent stain page says one coat is enough and a second adds more color. The default is 2, and you can edit it.
Does the calculator include labor or surface prep costs?
No. The cost shows only the stain, calculated from the price per can and sales tax you type. Labor, cleaner and prep are not included.
What if I enter a coverage outside 150 to 500?
The tool shows a warning. Check the coverage on your can and enter that figure instead.
Can I enter the deck size in square meters?
Yes. Choose m² next to the “Deck surface area” field and type the area. The tool converts it, because one ft² equals 0.09290304 m² exactly, and still reports gallons and cans.
Related tools
- Deck Board Calculator: use it to work out how many deck boards a project needs before you plan the finish.
- Deck Board Dimensions: use it to compare board sizes when you measure the deck surface.
- Cost to Build a Deck Calculator: use it if you are estimating the cost of a new deck rather than restaining one.
- Deck Joist Spacing Chart: use it to check joist spacing when you plan the frame under the deck.
- Stair Calculator: use it to plan the rise and run of deck stairs.
- Stair Stringer Calculator: use it to size the stringers for those stairs.