Wood Shrinkage Calculator — Dimensional Movement

Wood is hygroscopic — it absorbs and releases moisture from the air. As moisture content decreases below the fibre saturation point (around 28%), the wood cells shrink. Wood moves most across the grain (tangentially) and least along the grain (which is negligible).

The fibre saturation point (FSP) is the moisture content at which the cell walls are fully saturated but there is no free water in the cell cavities — typically around 27–30%. Below this point, further drying causes the wood to shrink. Above it, additional moisture causes no dimensional change.

In the UK, indoor furniture should be at 8–10% moisture content. For centrally heated rooms, aim for 8%. For less-heated spaces, 10–12% is appropriate. Outdoor furniture should be around 14–18% MC.

Yes, significantly less. Quarter-sawn boards shrink and expand radially (across the rings), which is typically about half the tangential movement of flat-sawn boards. This is why quarter-sawn timber is preferred for tabletops, drawer sides, and panel construction.

Use a pin-type or pinless moisture meter. Pin meters are more accurate for specific depths; pinless meters scan larger areas. For woodworking, a meter accurate to ±1% MC is sufficient. Always take readings from the middle of the board, not the ends.