Air-Dry Lumber Time Calculator
Estimate how long green lumber needs to air dry to reach a usable moisture content.
Based on species, board thickness, and drying location.
The Classic Rule of Thumb
The most widely cited guideline is one year of air drying per inch of board thickness for hardwoods, and about six months per inch for softwoods. This assumes drying from green (roughly 30 to 40% moisture content) down to air-dry (12 to 15%), stacked with stickers in a covered outdoor location.
This is a rough approximation. Actual drying time depends heavily on species density, board width, local climate, and stack management.
Why Moisture Content Matters
Wood moves with changes in moisture. Furniture built from under-dried lumber will crack, warp, and open at joints as it continues drying indoors. For indoor furniture, target 6 to 8% moisture content (equilibrium with a heated interior). Air drying only gets you to 12 to 15% in most climates. Kiln drying or in-shop conditioning is needed for the final step.
Species Differences
Dense, slow-growing hardwoods like hickory, white oak, and hard maple take longer to dry than lighter species. Softwoods like pine, cedar, and spruce dry quickly. Very dense tropical hardwoods (ipe, teak) can take 2 to 3 years per inch.
Location Factors
Outdoor covered stacking (under a shed roof, good airflow) is the baseline. An indoor unheated building speeds things up slightly by reducing rain wetting cycles. A heated indoor space speeds drying significantly but requires careful monitoring to prevent case hardening, where the surface dries too fast and traps moisture inside.
Sticker Spacing
For best results, use dry stickers (typically 3/4 by 1-1/2 in) spaced 12 to 18 inches apart. Weight or strap the top of the stack to reduce cupping. Align stickers vertically above each other in the stack. Good airflow across all faces is more important than any single rule.