Hi! I am Scott Paul, a leading exterior restoration contractor and business owner with over 30 years of experience in exterior wood staining and restoration. My tips on how much deck stain to buy are based on my history as a wood restoration contractor and actual hands-on project experience. See here for more info about me.
How Much Deck Stain Should I Buy?
Before staining a deck you need to figure out the deck’s total square footage. Once this calculation is considered, you can figure out how many gallons of deck stain you need by reading the coverage rate of the stain you are buying. On average most deck stains cover 150 to 300 sq ft per gallon depending on the age, condition, and porosity of the wood.
- Measure total square footage by adding floor (length x width), railings (linear length x height), and steps (width x number of steps)
- Most deck stains cover 150 to 300 sq ft per gallon on the first coat — second coats cover up to 50% farther
- New wood under one year old needs only one coat of transparent, semi-transparent, or semi-solid stain
- Always buy 10 to 15 percent more than your estimate — you can return unopened cans or save them for maintenance
- Use the interactive deck stain calculator for a precise gallon estimate based on your exact dimensions
Contents
- How to Measure Your Deck
- Estimated Gallons by Deck Size
- Coverage Rate by Stain Type
- New Wood: One Coat Rule
- How Much Prep Product to Buy
- Pro Buying Tips
- Use the Deck Stain Calculator
- Recommended Deck Stains
- Frequently Asked Questions
How to Measure Your Deck Square Footage
Getting an accurate square footage is the most important step before buying stain. Follow these steps to measure every section of your deck.
- Measure the deck floor. Multiply the length by the width and write that number down. If your deck has a second tier or stair landing platforms, measure those separately and add them to the floor total.
- Measure the railings. Measure the total linear feet of all handrails including stair railings. The average railing height is 3 feet. Multiply the total linear feet by the height to get your railing square footage.
- Measure the steps. Count the total number of steps and measure their width. Multiply the step width by the number of steps to get your stair square footage.
- Add all three sections together. Floor square footage plus railing square footage plus stair square footage equals your total deck square footage.
- Add any extra structures. Include lattice, skirting, built-in benches, pergolas, or any other wood structures you plan to stain.
My Pro Tip: If you don’t have a tape measure, you can approximate by stepping the deck off with long strides. A long stride is close to a yard, which equals 3 feet. Multiply the number of strides by 3 to get your approximate footage. A measuring wheel is even more accurate for larger decks.
Estimated Gallons Needed by Deck Size
Use this table as a quick reference for common deck sizes. These estimates are based on two coats of semi-transparent stain on average weathered wood, including floor only. Add 20 to 30 percent more if you are also staining railings and steps.
| Deck Size (Floor Only) | Estimated Gallons (2 Coats) | Estimated Gallons with Railings and Steps |
|---|---|---|
| 100 to 200 sq ft | 1 to 2 gallons | 2 to 3 gallons |
| 200 to 300 sq ft | 2 to 3 gallons | 3 to 4 gallons |
| 300 to 400 sq ft | 3 to 4 gallons | 4 to 6 gallons |
| 400 to 500 sq ft | 4 to 5 gallons | 6 to 8 gallons |
| 500 to 700 sq ft | 5 to 7 gallons | 8 to 11 gallons |
| 700 to 1,000 sq ft | 7 to 10 gallons | 11 to 15 gallons |
Coverage Rate by Stain Type
Coverage varies significantly depending on what type of stain you are using and the condition of your wood. Use this as a reference when calculating your purchase.
| Stain Type | Coverage Per Gallon (1st Coat)* | Notes |
|---|---|---|
| Semi-Transparent Oil-Based | 150 to 250 sq ft | Penetrating; weathered wood absorbs more |
| Semi-Transparent Water-Based | 150 to 200 sq ft | Film-forming; coverage more consistent |
| Semi-Solid Stain | 150 to 250 sq ft | Heavier pigment load; coverage varies by brand |
| Solid Color Stain | 150 to 300 sq ft | Two coats required; second coat covers more |
| * Coverage rates shown are per coat on the first application. Second coats typically cover up to 50% farther than the first coat, as the wood has already absorbed its initial saturation. | ||
New Wood: The One Coat Rule
If your deck is less than one year old and you are using a transparent, semi-transparent, or semi-solid stain, apply only one coat. New wood is denser and less porous than weathered wood and will not absorb a second coat properly — the excess stain will sit on the surface and cause premature peeling or blotching. This significantly reduces the amount of stain you need to buy for a new deck project.
For full guidance on timing and prep for new wood, see our article: How Long Should You Wait to Stain a New Deck?
How Much Prep Product to Buy
Stain is only part of the purchase. Before you stain, you need to prep the wood properly. Coverage estimates below are based on Restore-A-Deck Prep Products, our recommended prep system.
| Prep Product | Typical Coverage | When You Need It |
|---|---|---|
| Deck Cleaner | 500 to 1,000 sq ft per kit | New or lightly weathered wood with no old stain |
| Deck Stain Stripper | 500 to 1,000 sq ft per kit | Any deck with old or failing stain that needs removal |
| Wood Brightener | 500 to 1,000 sq ft per kit | Always — used after cleaning or stripping to neutralize pH |
Pro Buying Tips
- Always buy extra. It is better to have a partial gallon left over than to run short mid-project. You can return unopened cans to most retailers or save them for future maintenance coats.
- New wood under one year old gets one coat only. For transparent, semi-transparent, and semi-solid stains on wood less than one year old, apply only one coat. New wood is denser and will not absorb a second coat. See our full guide on staining new decks.
- Factor in two coats on bare or stripped wood. The first coat absorbs deeply and uses the most product. The second coat absorbs up to 50 percent less because the wood is already partially saturated — calculate both separately rather than simply doubling the first coat amount.
- Adjust for wood porosity. Older, heavily weathered wood can use 20 to 40 percent more stain than the label coverage rate suggests. New or smooth wood will use less.
- Don’t forget railings and steps. Most homeowners underestimate how much stain goes on railings and stair stringers. Always include these in your total before buying.
- Save leftover stain. Seal opened cans tightly and store in a climate-controlled space. Most oil-based stains stay usable for 1 to 2 years after opening and can be used for future maintenance coats.
Use the Deck Stain Calculator
For a precise gallon estimate based on your exact deck dimensions, stain type, wood condition, and number of coats, use our interactive tool. It calculates floor, railings, and steps separately and adjusts for wood condition automatically.
Use the Free Deck Stain Calculator
Recommended Deck Stains
Once you have your square footage and gallon estimate, find the right product for your deck below.
Frequently Asked Questions About How Much Deck Stain to Buy
How many gallons of deck stain do I need for a 400 square foot deck?
For a 400 square foot deck floor using two coats of semi-transparent stain on average weathered wood, plan on 3 to 5 gallons. If you are also staining railings and steps, add another 1 to 2 gallons depending on how much railing your deck has. Always buy a little extra — a partial leftover gallon is far less costly than running short mid-project and having to wait for a new order.
How do I calculate how much deck stain I need?
Measure your deck floor (length x width), your railings (total linear length x height), and your steps (width x number of steps). Add all three together for your total square footage. Divide by the coverage rate per gallon of your chosen stain — typically 150 to 250 square feet for the first coat — then multiply by the number of coats. For a faster calculation, use our interactive deck stain calculator.
Does the type of stain affect how much I need to buy?
Yes, significantly. Semi-transparent oil-based stains typically cover 150 to 250 square feet per gallon on the first coat. Solid color stains cover 150 to 300 square feet. Water-based semi-transparent stains cover 150 to 200 square feet. Weathered or porous wood absorbs more stain and reduces coverage toward the lower end of any range, so always factor in your wood’s condition when estimating.
Should I buy more stain than I calculate?
Yes — always buy 10 to 15 percent more than your calculated estimate. Wood porosity varies board to board, application technique affects how much product you use, and running short mid-project can cause visible lap marks if the stain dries before you can finish. Unopened cans can be returned to most retailers, and opened cans store well for 1 to 2 years if sealed properly.
How much stain do I need for deck railings?
A good rule of thumb is to measure the total linear length of all your railings including stair railings, then multiply by the average height of 3 feet to get square footage. A typical 300 square foot deck with railings on three sides will have approximately 100 to 150 square feet of railing surface — enough to add 1 to 2 gallons to your total purchase depending on the stain type and number of coats.
How much deck stain do I need for a new deck?
New wood under one year old that is being stained with a transparent, semi-transparent, or semi-solid stain only needs one coat. This significantly reduces the amount you need to buy — roughly half what you would use on a weathered deck requiring two coats. For a new 300 square foot deck floor, one coat of semi-transparent stain typically requires 1 to 2 gallons. See our guide on how long to wait before staining a new deck for full timing and prep guidance.
Can cleaner be used around medal spindals
No way to awnswer the 100% correctly this as it would vary based on the cleaner and the spindles themselves. Best to always test a spot first.
Best way to stain around medal spindals? Do I need to use oil base stain to wipe off stain that might get on medal spindals?
That vary based on if the metal spindles have a smooth coating over them or if they are powdered coating. Pics would help.
We have just power washed our 850 sq, foot 17 year old, south facing deck. The wood is in good condition. We plan to sand it next with a random orbital sander. What is your recommendation for a Maritime climate and for a product that will last longer than 2-3 years? Is there a sealant or stain that wouldn’t require all the initial preparation and just a yearly top coat?
Sanding tips: https://www.deckstainhelp.com/how-to-sand-your-wood-deck/
You cannot apply a sealer over a deck stain, it would peel. Try the TWP 1500 Series or the Restore A Deck Wood Stains.
How many gallons is stain will I need to cover 1100 square feet ?
That depends on the brand and type of stain you are using?
How many hours should it take to apply 1000’gallons of stain
There is no way to answer this question as it will vary drastically based on the stain type, stain brand, application method, and most importantly, user experience.
I asked your website twice how much does 1 gallon of Olympic stain semi transparent cover on a deck your website does not answer that
No, you never asked this question anywhere on our website. We checked and we would have answered if you had.
If I have a shed 10′ wide by 16′ deep by 14 ‘ tall with a aluminum roof. What amount of stain waterproof sealant would I need?
What is the total sq footage of all wood added up that is to be stained? Coverage also varies drastically based on the brand and type of stain being used so we will need to know that as well.
Is Olimpic maximum a good stain sealer?
No: https://www.deckstainhelp.com/olympic-maximum-stain-sealant-in-one-review/
I am in love with the deck at the very top of this web page. Was wondering what color that was so I could do my deck the same.
That is Restore A Deck Stain in Cedar color.
Will 5gal stain cover 18×16 deck floor
Coverage varies based on the stain brand, stain type, and how many coats are being applied so hard to say fer certain.
More than that your average stain will cover 450 to 600 ft.² but you will never get that answer from this website
No deck stain covers 450-600 sq feet per gallon. About half of that is average for 1 gallon.
16×20 deck and 3 stairs how much stain
Read the steps in the article above to add up and then check with the stain brand you are using to see the sq footage needed.
How many gallon 12×12
Depends on the brand, type of stain, and how many coats that need to be applied.
It’s Thomson water seat /Timber oil
Probably 1-2 gallons but not 100% sure as we do not use the Thompsons, it is a very poor product.https://www.deckstainhelp.com/thompsons-deck-stain-review/
I am staining a 8by8 porch how much stain do I need
Depends on the brand and type of stain.
How many gallons does it take to seal 384 square feet with Penofin oil Ipe wood
For IPE wood? About 2 gallons.
I live on a lake in Indiana, so the walkway, deck and pier are exposed to intense heat and cold. It is a 11 years old and comprised of pressure treated pine. I have power washed the deck and restained every 3 years. The boards are now starting to cup. In the shaded areas they have mold and mildew. The total square footage is approximately 2,000 sq feet. What product do you recommend, how much should I buy, and best method of application?
Thank you
Dean
Try the Armstrong Clark stains or TWP 1500. Coverage varies but about 15-20 gallons for the two coats. Apply with stain pads and brushes.
We are refinishing an older wood deck. It is now powerwashed, drying. There are some open holes….where there were knots that have fallen out. Do those need to be FILLED prior to applying stain? If so, what product and how to do it….thanks
No, and wood filler does not work on exterior wood. Just leave as is.
Best way to apply semi solid oil stain on old deck
Best “dark chocolate ” color stain that will last the longest.
Try TWP 1504 Dark Oak or Armstrong Clark Black Walnut.
I have a 20x 20 deck railings the same 4 steps 4×6 how much sealer would i need?
Please read the above on how to measure all and then add up. The next step would be to determine what stain you are using, how many coats needed, etc.
Just had 500 sq. Deck installed with rails and 3 sets of steps. What’s the best dealer and best way to apply it
I meant sealer, not dealer. Thank you
See here about new wood: https://www.deckstainhelp.com/staining-a-new-deck/
After I stain my new treated pine deck will it take the same amount of stain for the second coat or less. How do I figure how much for the second coat?
About the same amount.
How many gallons of stain I need to cover a 9×11, 99 square foot deck for 2 coats and one coat underneath?
It depends on the brand and type of stain as coverage varies.
I have a new redwood landing and stairs. About 50 square feet. How much sealer do I need to buy?
Depends on the brand but 1 gallon should cover it.
How much deck stain does it take for 375 square ft
Depends on the brand and type of stain you are using?
I HAVE 27′ x 40′ deck and need to know how much Thompson clear water seal will it take?
Thompsons is a useless product: https://www.deckstainhelp.com/thompsons-waterseal-finish-review/
As for how much is needed. About 10-15 gallons if you decide to use it.
lol what brand do you recommend?
All clear sealers will not provide UV protection from graying. Best to use a penetrating semi-transparent stain like one of these: https://www.deckstainhelp.com/the-5-best-deck-stain-reviews-and-ratings/
How much Stain to cover 50 square metres ?
Depends on the brand and type of stain being used?
if i am staining a wardrobe 15 x 40 how much stain do i need
I do not understand your question. Coverage also varies on the stain brand and type you are using.
Does the above article generate to the amount of stain one needs for one coat?
One coat.
I am re-staining a deck that was done about 4 years ago. It has held up pretty well but will need a good cleaning and light sanding in spots. It is unclear whether on-line calculators used to estimate how much stain to buy assume that the deck has never been stained before or that the deck was stained previously. Would it be correct to assume that if I am using the same product/color in a semi-transparent (water based) that I would not need as much stain? The deck is about 540 sq ft. Thanks!
No. You will need the same amount as previously.
Thanks for the quick response!
You are welcome!
I’m in the Greater Seattle area and need and I’m looking for someone to stain, seal and waterproof my deck and soffits. I had a contractors come out and give me a bid, but I’m wondering if there’s a special way to measure the square footage as the numbers he gave me seem to be way over. I have rails, spindles, steps, soffits and lattice. I’ve measured the soffits and my numbers are significantly less than the contractor’s and my measurement is an over estimate that includes areas where the wood is cutout to for other structures. Their measurement was 375 sqft while mine was 343 sqft.
I would trust the contrator to measure correctly and it only a 32 difference in feet.
As a contractor myself I never give an estimate in which the number doesnt end in either zero or 5. If a contractor gave you a number like yours, 343 then they usually will end up needing more. Always round up. Here is why, you have waste in materials. You also have the fact that we havent been able to test to see how your wood will soak up the product. Many factors. Also, 32 square feet isnt a huge number. If he was 500 or 1000 square foot off then you would second guess it.
We bought a house with a deck of 350 square feet. The wood is very porous since it should have been done quite awhile ago. We power washed it and now want to apply ‘Woodsman’ premium ‘solid’ stain. How much should we buy?
Sorry but not familiar with that brand and coverage varies by the brand.
I would guess 2-4 gallons.
We just installed a new 14×16 redwood floating deck. this last week. No railings. How much stain do I need.
Hello, this varies drastically on the brand and type of stain you will be using. See this article on new wood: https://www.deckstainhelp.com/staining-a-new-deck/
My back yard deck is clear wood about 4 month old and it is 325 SQ feet , how much do I need to buy to stain it . and it is new do I need to clean it first
Yes prep with the Restore A Deck Cleaner kits. As for the stain needed, it varies on the brand you choose. Do you know which one you will be using?
No I do not know what brand I am going to use , I was looking to buy a big 5 gallon maybe . Thompson brand I think , or I would like to go Sherman Williams , it is 27 feet long nd 1feet wide ,
Roughly 3000 sq ft for a multiple level deck, railings, steps, lattice etc…..how much AC semitransparent stain for 2 coats? Decks was stained with same AC 3 Years ago
Do you remember how much you used last time? Should be about the same. AC spreads well but this is a big deck. Most likely you will need 15-20 gallons.
So I'm restaining my deck. I've striped and sanded the entire deck. Total sq ft is 555 sq ft. How many gallons of stain will I need?
Depends on the stain brand as they do not all coverage the same sq. footage. Have you choosen one yet?
How do I figure square footage of deck steps
Width of steps x the tread/riser combined. For the railings we multiply the height times the length.