Fence Slat Count Calculator for a Wood Fence or Screen
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/10/2026
The number of slats is calculated with fence length ÷ (slat width + spacing), rounded up. For 10 m of fence with 9 cm slats spaced 2 cm apart, you need 91 slats.
Explanation
A wood fence with vertical slats (a solid fence or a spaced screen) is built by repeating a regular pattern: a slat, then a gap, then a slat, and so on to the end. The number of slats is therefore found by dividing the total fence length by the pattern pitch — the width of one slat plus the desired gap between two slats. This calculation has no "extra slat at the end": unlike battens for a frame, which must be placed at each end (see our frame batten spacing calculator), a fence ends indifferently on a slat or a gap depending on the exact length, and rounding up is enough to cover the whole run. This calculator only covers the infill: the load-bearing posts and their setting are covered by our fence post spacing calculator, and a flexible mesh fence, with no rigid slats, follows an entirely different logic. The spacing between slats is an aesthetic and functional choice: at zero, the fence is solid and opaque (maximum privacy, but heavy wind load); spaced 2 to 5 cm apart, the slats let through a little light and especially air, which reduces the strain on the posts in strong wind.
Example: 10 m of fence, 9 cm slats spaced 2 cm apart
Inputs
Length: 10 m. Slat width: 9 cm. Spacing: 2 cm.
Calculation
Pattern pitch = 9 + 2 = 11 cm. Number of slats = 1000 cm ÷ 11 = 90.9, rounded up to 91.
Result
You need 91 slats to cover this 10 m fence.
Frequently asked questions
Why isn't there an extra slat at the end, like with posts?
Because a slatted fence is a repeating "slat + gap" pattern that continues to the end: depending on the exact length, it ends on a slat or a gap, without needing an extra slat. A set of posts or frame battens, on the other hand, requires an element at each end, hence the "+1" in those calculations — not here.
Should I order extra slats for cuts and defects?
Yes, it's wise to add 5 to 10% to the result to cover boards with a defect on delivery (a split, a through knot, a twist), angled cuts if the ground slopes, and adjustments at the fence ends. This calculator gives the exact theoretical count; the purchasing margin is up to you based on the batch quality.
Does this calculation work for horizontal slats?
Yes, the principle is identical: just reason about the fence height rather than its length, and multiply the resulting slat count by the number of bays between posts (horizontal slats are usually cut to one bay's length). Enter the fence height in the "length" field in that case.