Stain Calculator
How much wood stain do you need? Calculate the exact gallons for your deck, fence, siding, or furniture based on stain type, wood porosity, and number of coats.
Surface Dimensions
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Last updated June 23, 2026 by our expert review team
Which Opacity? Coverage, Lifespan & 10-Year Cost
Transparent looks best but re-stains soonest. Solid lasts longest. See the real 10-year cost.
Over 10 years, solid / opaque is cheapest at $200 — it re-stains only every ~5 yr. A transparent finish shows the most grain but needs re-coating ~7× in the same span. Pick on looks vs. upkeep, not just the can price.
One-coat coverage; vertical fences and shade last longer than sun-baked horizontal decks. Material only, US averages.
Choose Stain by Project
Start with the wood and exposure, then use the calculator to adjust for coats, absorption, and the actual surface area.
Deck boards
Semi-transparent or semi-solid
Horizontal wear and standing water usually call for two thin coats.
200-300 sq ft/gal
Fence panels
Semi-transparent or solid
Vertical boards are easier, but rough-sawn cedar can drink stain fast.
150-300 sq ft/gal
Railings + end grain
Semi-solid or solid
Spindles have four faces, and post tops need extra attention.
150-250 sq ft/gal
New or weathered wood
Primer is not used, prep is everything
Let new pressure-treated lumber dry. Clean and brighten gray boards before staining.
reduce 15-25%
Expert Contributors
Cherry Jane Limbago
Licensed Civil Engineer & Master Plumber
Licensed civil engineer and master plumber with 10+ years in structural design, estimation, and project management. Currently Project Engineer at Universal Robina Corporation.
See full profileHawkin
Certified Cost & Estimating Professional
AACE-certified estimator working with 20+ insulation companies including the two largest franchises in America.
See full profileUpdated June 2026
How we verify our calculators
Coverage by Stain Type
ft²/galPer gallon on smooth wood. Rough-sawn boards can reduce coverage 30-40%; weathered smooth boards often reduce coverage 15-25%.
Which Stain for Which Surface?
Shows grain, good protection
Maximum weather protection
Natural wood beauty
Paint-like coverage, durable
Preserves cedar character
Rich color, some grain visible
Wood Type & Stain Absorption
Softwood
+15%
15-20% more absorption
Hardwood
-10%
Lower absorption
Pressure-Treated Wood
0%
Standard absorption
Composite/Engineered
-25%
Minimal absorption
Pro Tips
Always back-brush after rolling or spraying. Stain needs to be worked into the grain to penetrate evenly. Back-brush within 10 to 15 minutes of application.
Check wood moisture with a pin meter before staining. Pressure-treated lumber needs to dry below 15% MC, which takes 3 to 6 months. Staining wet PT wood causes peeling within one season.
Ready Seal requires no back-brushing and works at any temperature, making it ideal for beginners. Coverage drops to about 150 sq ft/gal on thirsty softwood.
TWP 1500 Series (oil-based) penetrates hardwoods like ipe and mahogany best. Plan for 200 to 250 sq ft/gal on dense tropical hardwoods versus the label's 300 sq ft/gal claim.
Wait 48 to 72 hours after pressure washing before staining. Use the sprinkle test: flick water on the wood, and if it beads instead of absorbing within 10 seconds, it's not ready.
Olympic Elite semi-transparent covers about 250 sq ft/gal on smooth surfaces but drops to 150 to 175 sq ft/gal on rough-sawn cedar. Rough-sawn boards can use 30-40% more stain than smooth boards, so calculate from actual texture, not just the label rate.
How the Calculator Works
The calculator multiplies your surface dimensions to get total square footage, then divides by the coverage rate for your selected stain type. Wood absorption changes that rate. Softwoods usually need 15-20% more stain than dense hardwoods, and rough-sawn boards can need 30-40% more than smooth boards.
Label coverage assumes smooth wood and good conditions. A second coat often spreads 20-25% farther because the first coat has sealed some pores, but this calculator keeps full-coat math so you do not under-buy. For wall coatings, use the paint calculator instead.
Formula
Gallons = (Area ÷ Coverage Rate × Absorption Factor) × Coats
Example: (240 sq ft ÷ 250 sq ft/gal × 1.15) × 2 coats = 2.2 gal
Quick Reference
- Transparent coverage
- 300 sq ft/gal
- Semi-trans coverage
- 250 sq ft/gal
- Solid coverage
- 175 sq ft/gal
- Softwood absorption
- +15-20%
- Rough-sawn boards
- +30-40%
- Second coat
- 20-25% farther
- Deck coats needed
- 2 coats
Frequently Asked Questions About Wood Stain
Is deck stain different from fence stain?
Yes. Deck stains have more resin and UV blockers for foot traffic and standing water. Fence stains are thinner for vertical surfaces. You can use deck stain on a fence, but fence stain on a deck wears through in one season.
How often should I restain my deck?
Transparent stains last 1 to 2 years, semi-transparent 2 to 3 years, and solid stains 4 to 5 years. Splash water on the deck; if it soaks in within 30 seconds, it's time to restain.
Should I pressure wash before staining?
Yes, but keep the nozzle at 25-degree fan, stay 8 to 12 inches from the surface, and never exceed 1,500 PSI on softwood. Wait 48 to 72 hours before staining.
Which stain type should I choose?
Transparent shows full grain but lasts only 1 to 2 years. Semi-transparent balances grain visibility with 3-year durability. Solid hides the grain but lasts 4 to 5 years.
Can I stain pressure-treated wood right away?
No. New PT lumber has 40 to 60% moisture and needs 3 to 6 months to dry below 15%. Use a pin moisture meter to test before staining.
Do I need to sand before staining?
For new wood, light sanding with 80 to 100 grit removes mill glaze that repels stain. For previously stained wood, only sand if the old finish is flaking.
What's the best temperature for staining?
Apply between 50 and 90°F with no rain forecast for 24 to 48 hours. The ideal range is 60 to 75°F with low humidity. Avoid direct sunlight.
Oil-based vs water-based stain?
Oil-based penetrates deeper and lasts 20 to 30% longer, especially on hardwoods. Water-based dries faster (2 to 4 hours vs 24 to 48 hours) and has lower VOCs.
Wood Stain Estimates for Common Projects
12x20 ft Pressure-Treated Deck
300 sq ft total | Semi-transparent, 2 coats | 2.5 gallons | ~$100
Tip: Railings have 4 exposed faces, so multiply linear footage by the combined widths, not just one side.
150 ft Cedar Privacy Fence
900 sq ft (one side) | Transparent, 1 coat | 5 gal one side / 10 gal both | ~$175-350
Tip: Rough-sawn texture cuts label coverage by 30-40%. Budget for 4.5 gal per side, not the 3 gal the label math suggests.
Pergola with 6x6 Posts and Rafters
192 sq ft | Semi-solid, 1 coat | 1 gallon | ~$45
Tip: End-grain on post tops absorbs 3-4x more stain than face grain. Seal end grain first or budget an extra quart.
Wood Stain Mistakes That Cost You Money
Staining in direct sunlight
Above 90°F surface temp, stain dries before penetrating and peels within weeks. Work in shade or start early morning.
Skipping the moisture meter check
New PT wood arrives at 40 to 60% moisture. Staining before it drops below 15% traps water inside, causing bubbles and peeling. A $25 pin meter pays for itself on one project.
Applying too much stain per coat
Excess stain sits on the surface and becomes sticky or flaky. Apply thin coats and back-brush excess within 15 to 20 minutes.
Not cleaning between old stain and new
Fresh stain over dirt or degraded finish won't adhere. Use a deck cleaner and stiff brush before pressure washing to break down the oxidation layer.
Mixing oil-based over water-based
Oil and water-based stains don't adhere to each other. Test with denatured alcohol: if color comes off, it's water-based. If not, it's oil-based.
Ignoring weather windows after application
Oil-based stains need 24 to 48 hours dry; water-based need 4 to 6 hours. Rain during the cure window washes out pigment and leaves blotchy areas.
Important Disclaimer
These estimates are for planning purposes only. Actual costs vary by location, material availability, and project complexity. Always get at least 3 local quotes. This calculator does not replace professional advice.
Sources
See 12 deck stain color ideas
Browse the looks, then price yours here.