Drying Room Calculator

It's built on the standard cannabis wet-to-dry ratio, where roughly 75% of the plant's harvested weight is water that evaporates during the 10-14 day dry. The calculator applies this as a fixed 0.25 multiplier to your wet harvest input, so a 100 lb wet harvest is projected to finish at 25 lbs dry regardless of strain — actual dry-back can vary a few points either way depending on trim density and cure conditions.

Hanging assumes about 1 lb of wet weight per linear foot of line spaced 2 feet apart in 8-foot runs, with a 40 sq ft floor minimum, while rack drying assumes roughly 2 lbs wet weight per square foot of shelf using 4-shelf, 4×4-foot racks plus floor space for access. Rack drying generally packs more wet weight into a smaller footprint since it stacks vertically across four shelves, so switching methods for the same harvest weight can noticeably shrink or grow the required room size.

The calculator applies a 2% faster drying rate for every degree above 60°F, so the adjusted drying days figure divides your target days by that speed-up factor. Drying faster at higher temperatures trades off against terpene retention, though, which is why the tool's guidance still recommends staying in the 60-65°F range rather than cranking heat purely to shorten the schedule.

Mold risk is scored purely from your target relative humidity input: LOW at or below 60%, MODERATE from just above 60% up to 65%, and HIGH above 65%, since trapped moisture at elevated humidity is the primary driver of mold and bud rot during cure. That same moisture load also drives the required pints-per-day dehumidification figure, so a higher target RH doesn't just raise your mold-risk score — it also lowers the amount of water the room needs to shed, which can understate real-world dehumidifier needs if your room leaks humid air in from outside.