Deck Stain/Sealer Calculator
Stop guessing how many cans of stain to buy. Enter your deck’s dimensions, pick a product type, and set the number of coats to get the gallons, cans, and cost for the job.
Prefilled from the selected product — adjust to match your can label or surface porosity.
Covers spills, absorption, and touch-ups. 10–15% is normal.
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Application tips
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Coverage & coats
Product profile
Gallons needed equals your deck’s square footage, multiplied by the number of coats, multiplied by 1 plus your waste percentage, divided by the product’s coverage rate in square feet per gallon. Coverage rate varies by product: solid color stain runs around 200 sq ft per gallon, semi-transparent stain around 250 sq ft per gallon, and clear water repellent sealer around 300 sq ft per gallon, since it goes on thinner. Round the gallon total up to the nearest whole can based on the can size you’re buying.
Deck Stain and Sealer Coverage Rates
Coverage varies by product type and by how weathered or porous the decking is. Rough-sawn or older wood soaks up more product than smooth, newer boards.
| Product Type | Coverage per Gallon | Best For |
|---|---|---|
| Solid color stain | 150-200 sq ft/gal | Older or patched decking; hides grain and wear |
| Semi-transparent stain | 200-300 sq ft/gal | Cedar and pine decks; shows wood grain with tint |
| Clear water repellent sealer | 250-400 sq ft/gal | Moisture protection only, no color; reapply every 1-2 years |
How to Calculate Deck Stain and Sealer
- Measure the length and width of your deck to get total square footage.
- Choose your product type and confirm its coverage rate per gallon.
- Set the number of coats; most stains need 2 coats, sealers often need just 1.
- Add waste for spillage, brush loss, and touch-ups.
- Divide the total by coverage per gallon, then round up to whole cans.
Worked example
A 16 x 12 ft deck (192 sq ft), stained with semi-transparent deck stain in 2 coats, with 5% waste added.
- Deck size16 x 12 ft = 192 sq ft
- Coats2
- Coverage rate250 sq ft per gallon
- Waste added5%
- Total gallons needed1.61 gallons
- Cans to buy2 (1-gallon cans)
- Total cost2 x $38 = $76
Weather and Timing for Stain Application
Deck stain and sealer need dry wood and dry weather to cure properly. Wait at least 48-72 hours after rain, and don’t apply if rain is forecast within 24-48 hours of finishing. Ideal application temperature is 50-90 degrees F, out of direct sun on the surface you’re working on so the product doesn’t flash-dry before it soaks in. A new pressure-treated deck should weather for several weeks to a few months before staining so the wood can accept the product; a water-bead test (splash on some water and see if it beads up or soaks in) tells you if the deck is ready.
Common mistakes
- Not counting both sides of railings and balustersRailings, balusters, and stair components add real square footage that’s easy to forget when you only measure the deck floor.
- Skipping the waste percentageBrush and roller loss, spills, and touch-up coats add up; buying exactly to the calculated minimum often leaves you short.
- Assuming 1 coat is enoughMost stains are formulated for 2 coats to get full color and protection; check the product label before you cut the estimate to 1 coat.
- Buying the wrong coverage rate for weathered woodOlder, rough, or previously stripped decking is more porous and will drink up more product than the can label’s coverage rate assumes.
What this calculator assumes
Adjust your result if your project differs from these.
- Deck area is entered as a simple rectangle (length x width); complex shapes should be measured as separate sections and added together.
- Coverage rate is the manufacturer’s stated square feet per gallon for that product type.
- The same coverage rate and coat count apply to the entire deck.
- Waste percentage accounts for spillage, brush loss, and touch-ups, not a full extra coat.
- Cans are rounded up to whole units of the size selected; partial cans aren’t sold.
Common questions
How many coats of deck stain do I need?
Most deck stains are designed for 2 coats to reach full color depth and protection. Clear sealers are often applied in just 1 coat since they’re meant to be more transparent.
Does solid or semi-transparent stain cover more area?
Solid color stain generally covers less area per gallon than semi-transparent, because it lays down a thicker, more opaque film.
How long does deck stain last?
Semi-transparent and solid stains typically last 2-3 years before needing a refresh coat; clear water repellent sealers usually need reapplication every 1-2 years.
Should I include stairs and railings in my square footage?
Yes. Measure the deck floor, then add the surface area of railings, balusters, and stair treads/risers separately since they use noticeably more product per square foot of coverage.
Can I mix leftover stain from a previous year?
Only if it’s the same product and color; different formulations or batches can cure to slightly different sheens and colors when applied side by side.
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Deck Stain/Sealer Calculator Estimate
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Project
| Shape | — |
| Dimensions | — |
| Area | — |
| Product | — |
| Coverage | — |
| Coats | — |
| Overage allowance | — |
Shopping list
| Total product | — |
| Cans needed | — |
| Estimated total cost | — |
Notes
Estimate generated by materialcalculate.com. Confirm quantities and coverage with your product label before ordering.