How Much Will a 12 Inch Sapele Panel Move
+0.1776" (+4.5 mm)
- Species: Sapele (tangential shrinkage 7.4%)
- Starting width: 12"
- Moisture content: 6% -> 12% (a typical dry-to-humid seasonal swing)
MethodΔD = D x ΔMC x (shrinkage% / 30 / 100)
Your actual humidity swing may be smaller or larger than the 6-12% MC example used here — run your own numbers in the movement calculator.
A 12" wide sapele panel will grow about +0.1776" (+4.5 mm) across its width from 6% to 12% moisture content — nearly double the figure for Honduran mahogany at the same width, which matters because sapele is routinely sold and chosen as a mahogany substitute.
Why this one specifically
Sapele's interlocked grain and reddish-brown colour make it a convincing visual stand-in for genuine mahogany, and it's marketed that way often enough that some builders assume the two woods behave alike in service too. The movement numbers say otherwise: sapele's tangential shrinkage (7.4%) is closer to black walnut's than to mahogany's 4.1%, so a design built around mahogany's famously low movement and executed in sapele instead needs the wider panel-groove allowances and expansion gaps a less-stable wood requires, not the tighter ones mahogany would tolerate.
What moves the number
This number tracks width in a straight line — double the panel, double the movement. Sapele's pronounced interlocked grain also makes it more prone to tear-out during planing than mahogany — a machining difference, not a movement one, but worth knowing before treating the two as fully interchangeable.