Board and Batten Calculator (accent wall: battens, spacing & lengths to buy)

Understanding the board and batten calculator — concept and principle

This calculator plans a board-and-batten accent wall: how many vertical battens fit across the wall with equal gaps no wider than your target, the real gap and centre spacing, total batten length and how many stock lengths to buy, including optional top and bottom rails.

Battens across the wall: with the default inputs the result is 9 battens (28.8 m total).

How it is calculated

With a batten at each end: n = ⌈(W + gap) ÷ (b + gap)⌉, real gap = (W − n × b) ÷ (n − 1)

Without end battens: n = ⌈(W − gap) ÷ (b + gap)⌉, real gap = (W − n × b) ÷ (n + 1)

Centre-to-centre = real gap + b

Stock lengths for verticals = battens ÷ battens per stock length (or several lengths per batten if the wall is taller)

Rails run the full wall width at the top and bottom.

The principle

Equal spacing is the same arithmetic as balusters: n battens with an end batten at each side make n − 1 gaps across the wall. Rounding n up guarantees the gap does not exceed your target. Each stock length is cut into as many whole battens as fit, and rails need as many lengths as it takes to span the wall width.

Worked example

Default inputs: wall 360 × 240 cm, batten 7 cm, target gap 40 cm, battens at both ends, top and bottom rails, stock 240 cm.

n = ⌈(360 + 40) ÷ (7 + 40)⌉ = ⌈8.51⌉ = 9 battens.
Real gap = (360 − 9 × 7) ÷ 8 = 297 ÷ 8 = 37.1 cm; centre-to-centre = 44.1 cm.
Total batten length = 9 × 2.4 + 2 × 3.6 = 28.8 m.
Stock: 9 lengths for verticals, 4 for the two rails.

Each point is the calculator re-run with only “Largest gap you want between battens (cm)” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Largest gap you want between battens (cm)	Vertical battens
10	22
20	15
30	11
40	9
50	8
60	7
80	6

How to read the result

Add a few spare lengths for bad boards and miscuts. Check whether sockets and switches fall under a batten, and shift the layout slightly if needed. Walls are rarely perfectly square, so measure the width at top and bottom.

Common mistakes

Forgetting the rails when ordering.
Not allowing for skirting or ceiling trim that changes the height.
Fixing battens without a level, so small errors add up across the wall.

Keep in mind: Locate pipes and cables before nailing or screwing into walls.

Frequently asked questions

What gap is common for board and batten?

Often 30–50 cm, but it is a design choice.

Should I start at the centre or a corner?

Starting with a batten at each end keeps the layout symmetrical.

Do I need a backing board?

Not on a smooth painted wall; battens can be fixed directly.

Sources: Equal-spacing arithmetic (n pieces of width b across a width W with n − 1 or n + 1 equal gaps); no product-specific constants

Checked 9 Nov 2026. Equal-spacing arithmetic (n pieces of width b across a width W with n − 1 or n + 1 equal gaps) and whole-piece cutting from stock lengths; no product-specific constants.

Your numbers