Estimate air-drying time for guitar tonewoods. Enter species, thickness and moisture content to get drying days and weeks.
Pick the wood species, then enter the blank thickness in millimeters, the current (initial) moisture content, and the target moisture content as percentages. Drying happens species by species: spruce, cedar and basswood shed water fastest (about 0.10–0.11 mm of effective depth per day), while dense rosewood and ebony are the slowest at 0.05 and 0.04. Mahogany, ash, maple, walnut and alder sit in between, from 0.07 to 0.09.
The estimate scales with both thickness and the moisture gap: days = (thickness ÷ 25) × (MC difference ÷ 10) ÷ rate. A 50 mm mahogany blank going from 30% down to 8% (a 22-point drop, rate 0.08) works out to 55 days, about 7.9 weeks. A thinner 25 mm spruce top over the same 30→8% span dries in roughly 22 days (3.1 weeks), because halving the thickness halves the time.
Slow movers reward patience. A 50 mm walnut blank dropping from 40% to 8% (a 32-point gap at rate 0.07) needs about 91 days — roughly 13 weeks — before it settles. Aim for a final 6–8% moisture content to match indoor humidity, and remember this is an air-drying approximation based on Simpson's wood-drying principles, not a kiln schedule: airflow, stickering and ambient humidity all shift the real timeline.
Using this calculator, a 50 mm mahogany blank from 30% moisture content down to an 8% target works out to about 55 days — roughly 7.9 weeks — at mahogany's 0.08 effective drying rate. Real-world results vary from about 12 to 20 weeks depending on climate, stickering and air circulation, so treat the estimate as a planning floor.
Guitar tonewoods are typically worked at 6–8% moisture content to match indoor humidity. Building wetter than that invites shrinkage, sunken tops and lifting bridges later as the wood gives up moisture in a heated room.
Each species has its own effective drying rate per millimeter of thickness. Open-grained, lower-density woods like spruce, cedar and basswood release water quickly (0.10–0.11), while dense rosewood (0.05) and ebony (0.04) hold onto it. That is why an ebony blank can take more than twice as long as a spruce top of the same thickness.
In this model, yes — thickness enters the formula linearly. A 25 mm spruce top drying from 30% to 8% finishes in about 22 days (3.1 weeks), and a 50 mm blank of the same species over the same span takes about twice as long. Thicker stock dries disproportionately slowly in reality because moisture must travel farther, so err on the side of more time.