What this planner works out
You list the parts you will stain: deck top or boards, stairs, railing pieces, fence runs or boards, and anything you measured yourself, such as stringers. For each product you enter the coverage per coat from its label, the can sizes and prices you are comparing, and the surfaces and coats it goes on. The planner adds up the area per product, adds your own allowance, and rounds up to whole cans: exact quantity, with allowance, cans to buy, leftover and cost. A cleaner, brightener or stripper, and jointing sand for a block-paved patio, are planned from what one package or bag covers as sold. Patios, paths and driveways are a surface type of their own, for a sealer.
How each surface is measured
- Deck top: length × width. This is the top face only.
- Deck boards: number of boards × board length × face width of one board. The gaps are left out because you measure the faces.
- Stairs: steps × tread width × tread depth, plus steps × tread width × riser height if you stain the risers.
- Railing, posts or other pieces: how many × the perimeter you stain × the length or height of one piece.
- Fence run: run length × height × the sides you stain, times the solid share for an open fence.
- Fence boards or pickets: how many × face width × height × the sides you stain.
- Patio, path or driveway: length × width, or an area you measured yourself. Concrete, pavers or asphalt is a label only; the coverage comes from the label of your product.
Board edges and the gaps between boards add surface these formulas do not see, and the planner does not estimate it. Each surface has an edges and sides extra in percent, 0 by default, for your own figure; or measure the edges as a separate surface. For an open picket fence, the solid share is your own figure too: picket width ÷ (picket width + gap) × 100.
Worked example: a deck
A deck 12 × 16 ft has a top of 192 ft². Two coats at a label coverage of 250 ft² per gallon need 192 × 2 ÷ 250 = 1.536 gallons. In 1 gallon cans that is 2 cans, with 0.464 gallons left over.
If the label says 150 ft² per gallon for the first coat and 250 for the second, the two coats need 192 ÷ 150 + 192 ÷ 250 = 1.28 + 0.768 = 2.048 gallons. That is just over 2, so it is 3 cans. The planner never rounds down.
Worked example: a railing
Twenty balusters with a 6 in perimeter, 3 ft high: 20 × 0.5 ft × 3 ft = 30 ft². Two rails with a 10 in perimeter, 16 ft long: 2 × 10/12 ft × 16 ft = 26.67 ft². Three posts stained on faces adding up to 14 in, 42 in high: 3 × 14 × 42 ÷ 144 = 12.25 ft². Together that is 68.92 ft². Two coats at 250 ft² per gallon need 0.55 gallons, so 1 gallon can.
Worked example: a fence and two can sizes
A fence 100 ft long and 6 ft high, stained on both sides, is 100 × 6 × 2 = 1,200 ft². One coat at 200 ft² per gallon needs exactly 6 gallons, so 6 cans of 1 gallon, nothing left over. Anything above 6 gallons, even a little, would be 7 cans (see how pack rounding works).
With a 10% allowance it is 6.6 gallons. Say 1 gallon cans cost 45 and 5 gallon pails cost 180. On their own, that is 7 × 1 gallon for 315, or 2 × 5 gallons for 360. Mixed, 1 × 5 gallons + 2 × 1 gallon holds 7 gallons for 270, with 0.4 gallons left over. The planner shows this as the lowest total among the sizes and prices you entered.
A picket fence 50 × 4 ft, both sides, with a solid share of 70% and 10% extra for the edges: 50 × 4 × 2 = 400 ft², × 0.70 = 280 ft², × 1.10 = 308 ft².
Worked example in metric
A deck 4 × 3 m is 12 m². Two coats at 8 m² per liter need 24 ÷ 8 = 3 liters; with 10% allowance 3.3 liters, so 2 cans of 2.5 L (5 L), with 1.7 L left over.
Worked example: sealing a driveway or patio
A driveway 20 × 40 ft is 800 ft². Say the sealer label gives 80 ft² per gallon for the first coat and 100 ft² per gallon for the second. Two coats need 800 ÷ 80 + 800 ÷ 100 = 10 + 8 = 18 gallons. In 5 gallon pails that is 3.6, so 4 pails (20 gallons), with 2 gallons left over. Over both coats that works out at 1,600 ÷ 18 = about 89 ft² per gallon, which is why the two label figures matter: one figure of 100 ft² per gallon would have said 16 gallons.
In metric: a patio 6 × 3 m is 18 m². At 4 m² per liter for the first coat and 6 m² per liter for the second, 18 ÷ 4 + 18 ÷ 6 = 4.5 + 3 = 7.5 liters: 2 cans of 5 L, with 2.5 L left over.
Jointing sand for a block-paved patio of 16 m², with a label that says one bag fills 5 m² at your joint width and depth: 16 ÷ 5 = 3.2, so 4 bags. Joint size changes the figure a lot, so take it from the bag for your joints. The sand and the sealer are different products, so each is rounded on its own.
These numbers are examples to show the method, not a product’s values. Follow the product label for surface preparation, curing and weather.
Cleaner, brightener or stripper
These are often concentrates or kits, so you enter what one package covers as sold, for example “500 ft² per kit”. For the 192 ft² deck and the 1,200 ft² fence, one application needs 1,392 ÷ 500 = 2.78 kits, so 3 kits. There is no dilution or mixing maths: use the product as the label says, with the protective equipment it names.
The same product on several surfaces
Lines of the same product and color are added up before rounding. If one stain needs 1.2 gallons on the deck and 0.6 gallons on the stairs, that is 1.8 gallons: 2 cans, not the 3 you would get by rounding each surface on its own. A different color is a different product and is rounded on its own.
Replacement fence boards
Tick Count replacement fence boards to add the boards and fixings for an existing fence to the same plan. This counts replacement boards for posts and rails you already have. It does not check posts, rails, fixings or wind loads.
Each row is a group of identical bays. The boards are counted per bay: a board is never shared between two bays.
- Overlapped boards (featheredge, board-on-board): with bay width B, board width w and an overlap of at least o, each bay needs (B − o) ÷ (w − o) boards, rounded up.
- Spaced pickets with a gap at each post and no gap wider than g: each bay needs (B − g) ÷ (w + g) pickets, rounded up. The planner shows the gap they leave when spread evenly.
Six bays of 1.83 m with 100 mm featheredge boards overlapping by at least 25 mm: 1.805 ÷ 0.075 = 24.07, so 25 per bay and 150 boards. Dividing the whole 10.98 m run at once would say 147, three short. A bay of 96 in with 3.5 in pickets and gaps of at most 2.5 in: 93.5 ÷ 6 = 15.58, so 16 pickets, leaving gaps of 40 ÷ 17 = 2.35 in.
Boards are cut from the length they are sold in. Pieces of the same length come out of each board (4 ft pieces from 8 ft boards: 2 per board with no saw cut; any saw cut leaves room for only 1), with your saw cut between pieces; offcuts are not reused for other lengths, and a board shorter than the length needed is not joined. Fixings are each board × the rails it crosses × the fixings per crossing, from your count and the fixing pack: 150 boards × 2 rails × 2 nails = 600 nails, so 3 boxes of 250. Each board and fixing entry has its own allowance, 0% unless you enter one.
Limits and safety
This is a quantity estimate from your own measurements and label figures. It gives no advice on which product suits your wood, concrete, pavers or asphalt, on drying or curing times or on the weather. For a patio, path or driveway it is not a drainage, slope or structural assessment. It does not check boards, railings, stairs or posts for rot, loose fixings or strength. Have a qualified person check anything you are unsure of.
Rags soaked in oil-based stain or oil can heat up and catch fire on their own; follow the disposal instructions on the product label. In the United States, the NFPA publishes a safety tip sheet on oily rags; elsewhere, check your fire service’s guidance.