How long does it take to air dry wood?

The traditional rule of thumb is one year per 25mm (1 inch) of thickness for hardwood. Softwoods dry faster — roughly 6-9 months per 25mm. Oak is one of the slowest, often taking 2+ years for 50mm boards. Actual times vary with climate, airflow, stacking and time of year.

What is the difference between air drying and kiln drying?

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.

What moisture content should I 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.

What is case hardening?

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.

How should I stack wood for air drying?

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.

WoodCalcs

Wood Drying Time Calculator

Estimate drying time for timber based on species, thickness, moisture content and drying method.

Wood Species

Hardwoods dry slower than softwoods

Board Thickness

Thickest dimension being dried

Initial Moisture Content

Green wood is typically 40-80%

Target Moisture Content

8-10% for indoor furniture

Drying Method

Air drying is slowest, vacuum kiln is fastest

How We Calculate This

This calculator estimates wood drying time based on species characteristics, board thickness, moisture content range and drying method.

Key factors

Species: Dense, tight-grained hardwoods dry much slower than open softwoods
Thickness: Drying time increases roughly with the square of thickness
MC range: A larger moisture drop takes proportionally longer
Method: Kiln drying is 4-20x faster than air drying

Disclaimer

Drying times are estimates only. Actual times depend on climate, airflow, stacking quality, time of year and individual board characteristics. Always use a moisture meter rather than time alone to determine when wood is ready.

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Last updated: March 2026

All calculations are estimates. Always verify measurements and material quantities before cutting or purchasing.