Understanding your result
The headline is the stain or paint for the coats your product needs (or the number you entered), with the allowance, and the sub-line is the can list. The four figures show the area to coat, the coverage used, the quantity per coat and the cans.
The breakdown goes from the length including the gates, through the face area, the sides and the style factor, to the area to coat; then the product with its typical rough-wood coverage and usual coats, and the per-coat, allowance, total and can lines. If you entered a coverage from your can, the “coverage per coat” row shows yours and the product row still shows the typical figure for comparison.
Fences are a pail-sized quantity. Five-gallon pails are cheaper per gallon and the leftover keeps for the gate and the posts next year. The deck stain calculator uses the same products and condition logic for a deck; the sprayer usage calculator gives a closer overspray figure than the allowance if you are spraying; and the metal railing calculator is the one for a chain-link or iron fence.
How we calculate this
The face area is the rectangle the fence occupies. Gates add 4 ft of fence each, which is the width of a typical garden gate; a double driveway gate is two. The sides double it or not. The style factor then adjusts for what is actually there: a picket fence with 3.5 in pickets at 2.5 in gaps is about 60% board and the edges of the pickets bring it to about 70%; a shadowbox fence shows a full set of overlapping boards on each side, about 1.3 times the rectangle; horizontal slat fences with small gaps are about 95%. The fence staining guide explains the factors and how to estimate an unusual style.
The coverage figures are the rough-wood numbers from exterior stain data sheets, not the smooth-wood ones: 250 sq ft per gallon for clear sealers, 200 for semi-transparent stain, 175 for solid stain and 300 for paint over a primed fence. The coverage rates table lists the published ranges, and the deck stain guide has the porosity test that tells you whether your boards are at the high or the low end.
The assumptions behind the numbers
| Assumption | Default | Where it comes from |
|---|---|---|
| Clear or transparent sealer | 250 sq ft per gallon, 1 coat | Exterior sealer data sheets (Thompson’s WaterSeal, Behr Transparent): 150–300 on rough wood |
| Semi-transparent stain | 200 sq ft per gallon, 1 coat | Semi-transparent stain data sheets (Behr, Cabot, Olympic): 150–250 on rough wood |
| Solid-colour stain | 175 sq ft per gallon, 2 coats | Solid stain data sheets: 150–200 on rough wood |
| Exterior paint | 300 sq ft per gallon, 2 coats | Exterior acrylic over primer on rough wood |
| Gate | 4 ft of fence each | A standard garden gate |
| Style factors | solid 1.0, shadowbox 1.3, picket 0.7, horizontal 0.95 | Site estimates from the board geometry, explained in the fence guide |
| Allowance | 5% | Brush and pad loss; use 25–35% if spraying |
Assumptions last reviewed October 7, 2026.
The calculator does not model primer for a painted fence, which bare wood needs (the primer calculator takes an area), posts and rails as separate pieces (they are inside the face area), or the extra a very dry, grey fence drinks on its first coat, which can be a third more. Use your can’s rough-wood figure if it is lower than the default.
Two worked examples
A 100 ft privacy fence, both sides
6 ft solid board fence with one gate, semi-transparent stain at one coat, 5% allowance.
- Length: 100 + 1 × 4 = 104 ft; face: 104 × 6 = 624 sq ft
- Area to coat: 624 × 2 sides × 1.0 = 1,248 sq ft
- Per coat: 1,248 ÷ 200 = 6.24 gallons
- Needed: 6.24 × 1 × 1.05 = 6.55 gallons, buy a 5-gallon pail + 1 gallon + 3 quarts
Seven gallons in practice: a pail and two gallons. A picket fence of the same length, one side, in solid stain at two coats, would be 600 × 0.7 = 420 sq ft, 2.4 gallons per coat and 5.04 gallons in all: a pail and a quart.
A 150 ft shadowbox fence with two gates
6 ft high, both sides, semi-transparent stain, one coat.
- Length: 150 + 2 × 4 = 158 ft; face: 158 × 6 = 948 sq ft
- Area to coat: 948 × 2 × 1.3 = 2,465 sq ft
- Per coat: 2,465 ÷ 200 = 12.32 gallons
- Needed: 12.32 × 1.05 = 12.94 gallons, buy 2 pails + 3 gallons
Thirteen gallons, and a sprayer: the overlapping boards of a shadowbox cannot be brushed into, as the result’s note says. With a 30% overspray allowance instead of 5% it is 16 gallons, which the sprayer usage calculator will confirm with your tip and setting.
Where to find your inputs
Length. Pace it or run a tape along the bottom rail. Count every run, including the return to the house.
Height. From the ground to the top of the boards, not the posts. A 6 ft privacy fence is 6 ft; a 4 ft picket fence is 4 ft.
Gates. Count them; each is 4 ft of fence, both sides. A double gate is two.
Style. Solid board, shadowbox (alternating boards on both faces of the rails), picket (gaps), or horizontal slat. Lattice tops are mostly air; ignore them or count a foot of height for a 1 ft lattice.
Product. Read the can: sealer, semi-transparent, solid, or paint. The coats and the coverage follow.
Common mistakes
- Using the smooth-wood coverage. Fence boards are rough-sawn; the can’s low figure is the right one.
- Forgetting the second side. Both sides is double the stain and most of the reason people run short.
- Two coats of a penetrating stain. The second cannot soak in and stays sticky. One coat, wet-on-wet.
- Staining wet treated wood. Water-drop test first; new fences need weeks.
- Painting a fence that touches the ground. Paint peels at the soil line; stain weathers gracefully.
- Brushing a shadowbox fence. The overlaps cannot be reached; spray and back-brush.
Questions people ask
- How much stain does a 100 ft fence take?
- A 6 ft solid fence with one gate, both sides, is 1,248 sq ft. Semi-transparent stain on rough boards covers about 200 sq ft per gallon, so one coat with a 5% allowance is 6.55 gallons, a 5-gallon pail plus a gallon and three quarts. One side only halves it.
- Do I stain both sides of the fence?
- If you can reach both, yes. Boards finished on one side cup and weather unevenly, and the neighbour's side greys. A fence against a wall, a hedge or a neighbour who will not have it is a one-side job, and the calculator allows for that.
- How does the fence style change the quantity?
- Pickets have gaps, so a picket fence is about 70% of its face area; a shadowbox fence has boards overlapping on both sides, so each face is about 130% of the rectangle; horizontal slat fences are close to solid. The style factor multiplies the face area and is shown in the result.
- Which product and how many coats?
- Clear sealers and semi-transparent penetrating stains go on in one coat and cover 200 to 250 sq ft per gallon on rough wood. Solid-colour stains cover about 175 and take two coats. Paint covers more per coat but needs primer on bare wood and peels where boards meet the ground, which is why most fences are stained.
- Should I spray a fence?
- For anything over 50 ft, a pump sprayer or an airless rig with back-brushing is the practical method, especially on shadowbox and picket fences where a brush cannot reach the overlaps. Airless overspray adds 25 to 35% to the quantity; set the allowance to match, or use the sprayer usage calculator.
- Can I stain a new fence straight away?
- Pressure-treated wood needs to dry first, usually a few weeks to a few months depending on the weather. Sprinkle water on a board. If it beads, wait; if it soaks in within a minute, stain. Cedar and redwood can be stained once they are dry to the touch.