Wood Drying Time Calculator

The traditional rule of thumb is one year per 25mm (1 inch) of thickness for hardwood, down to ambient equilibrium moisture content. Softwoods dry roughly 2-3x faster — a 25mm pine board typically reaches ~20% MC in around 2-3 months. Oak is one of the slowest, often taking 2+ years for 50mm boards (drying time roughly quadruples when thickness doubles). Actual times vary with climate, airflow, stacking and time of year.

Air drying relies on natural airflow and can only dry wood to the ambient equilibrium moisture content (12-18% in the UK). Kiln drying uses controlled heat and humidity to reach lower moisture contents (6-12%) much faster. Most woodworkers air dry to 20-25% MC then kiln dry to their target.

For indoor furniture in centrally heated homes: 8-10% MC. For general indoor use: 10-12% MC. For outdoor furniture and joinery: 14-18% MC. For green woodworking: no drying needed. Going too far below equilibrium MC means the wood will re-absorb moisture and expand in use.

Case hardening occurs when the outer shell of wood dries and sets while the core is still wet. When the core eventually dries and tries to shrink, it creates internal stress that can cause the board to cup, split or honeycomb when cut. It is caused by drying too aggressively, especially in thick stock.

Stack on a flat, level surface raised off the ground. Place stickers (spacer sticks, typically 20-25mm square) between each layer, aligned vertically. Ensure good airflow on all sides. Weight the top of the stack to reduce warping. Cover the top to shed rain but leave sides open for airflow. Stack ends should be sealed with wax or end sealer.