Board On Board Fence Calculator
Get a shopping list for a board-on-board privacy fence. Enter fence length in feet, picket width and overlap in inches, post spacing, and rails per section — the calculator returns pickets, posts, and rails with a waste allowance.
Example: with Fence length (ft) 100 · Picket width (in) 5.5 · Overlap per side (in) 1 · Post spacing (ft) 8 · Rails per section 3 → Pickets needed: 280 pickets (2.67 per ft).
- Posts14 posts (13 sections at 8 ft)
- Rails39 rails (3 per section)
Computed by the calculator below using its default values. Change any input to see your own numbers.
Board-on-board averages one picket per (width − overlap) of fence run — a 5.5 in picket with 1 in overlap covers 4.5 in net, about 2.7 pickets per foot.
Why board-on-board uses more pickets
A board-on-board fence runs two staggered layers: back pickets with gaps, and front pickets centered over those gaps, overlapping each neighbor. Because every picket gives up its overlap on each side, the average coverage per board is just its width minus one overlap. A 5.5 in picket lapped 1 in covers 4.5 in of fence line — about 2.67 pickets per foot, roughly 25% more lumber than a side-by-side privacy fence.
The payoff is permanent privacy. Flat-laid pickets shrink as they dry and open sight gaps within a season; the overlapped layers keep the fence opaque even after shrinkage. Keep at least 3/4 to 1 inch of overlap so drying wood cannot pull the layers apart.
How it’s calculated
Pickets = fence length (in) ÷ (picket width − overlap), increased by the waste % and rounded up. Sections = ceil(length ÷ post spacing); posts = sections + 1 (straight run); rails = sections × rails per section. Defaults: 5.5 in pickets (a 1×6's actual width), 1 in overlap, 8 ft post bays, 3 rails for a 6 ft fence.
Assumes one straight run — gates, corners, and slope stepping each add posts and cut waste beyond the flat allowance.
Picket coverage at 1 in overlap
| Picket | Actual width | Net coverage | Pickets per ft |
|---|---|---|---|
| 1×4 | 3.5 in | 2.5 in | 4.8 |
| 1×6 | 5.5 in | 4.5 in | 2.67 |
| 1×8 | 7.25 in | 6.25 in | 1.92 |
Computed from standard US dressed lumber widths with a 1 in board-on-board overlap.
Common mistakes
- Using nominal width — a 1×6 picket is actually 5.5 in wide, and the missing half inch compounds over a long run.
- Counting overlap once per picket pair instead of per side: each board loses one overlap of net coverage, front and back rows alike.
- Forgetting the extra end post — 13 sections means 14 posts on a straight run.
- Skipping waste: split tops, culled boards, and cuts at posts typically consume 5% of pickets.
Frequently asked questions
How many pickets per foot does board-on-board take?
Pickets per foot = 12 ÷ (picket width − overlap). With 5.5 in pickets and a 1 in overlap that is 12 ÷ 4.5 = 2.67 pickets per foot, so a 100 ft fence needs about 267 plus waste.
How much should the boards overlap?
3/4 to 1 inch per side is standard. Less than that and the boards can shrink apart as they dry, opening sight lines the design is meant to prevent.
How many rails do I need?
Two rails for fences up to about 5 ft, three for 6 ft, and four for 8 ft. Rails count per section: a 100 ft run with 8 ft bays has 13 sections, so three rails each means 39 rails.
Is board-on-board more expensive than a standard privacy fence?
Yes — plan on roughly 20–30% more pickets for the overlap, plus the same posts, rails, and hardware. The return is a fence that stays fully private after the wood shrinks.
Does this include gates?
No. Add a post for each gate side, and buy gate hardware and a few extra pickets per gate leaf beyond the run calculated here.