Wood Movement Calculator
Predict seasonal expansion and shrinkage by species
How to use this wood movement calculator
Pick your species, enter the board width, and set the moisture content swing you’re planning for — the presets cover the most common scenario (humid outdoor storage to a heated indoor winter), but you can enter exact numbers if you’ve measured with a moisture meter.
Formula
Movement (in) = Width × Cm × (MC Change ÷ 100)
This is the standard simplified model from wood movement literature — it uses each species’ published average tangential shrinkage value and a general fiber saturation point assumption. It’s a solid planning number for sizing gaps in panel construction or breadboard ends, not a lab-precise prediction for any one board: flatsawn boards move more than quartersawn, and every board carries its own moisture history.
Why this matters
A wide panel glued up without room to move can crack, cup, or blow out a frame around it as humidity changes through the year. Sizing your grooves, slots, or breadboard gaps to this predicted movement — rather than guessing — is what keeps a solid wood panel flat and intact for years instead of one dry winter.