Mushroom growing calculators
Four free calculators for the numbers growers work out by hand: biological efficiency, spawn rate, cost per pound and Martha tent sizing. Each uses the formulas in our grower guides, which cite their sources, and none needs an account.
Which calculator do you need?
Biological efficiency calculator →
BE% from your harvest and your block's dry or wet weight.
BE (%) = total fresh weight of all flushes ÷ dry substrate weight × 100
Spawn rate calculator →
Spawn for a block or a batch, and what a bag of spawn covers.
Spawn = substrate weight × spawn rate ÷ 100
Cost per pound calculator →
What a fresh pound costs you, with lost blocks and overhead.
Cost per pound ≈ cost per block ÷ (fresh pounds per fruiting block × share of blocks that fruit)
Martha tent calculator →
Tent size, humidifier output and running cost.
Blocks a tent holds = shelves × 4, less one shelf if the fan sits on the top one
Keep the numbers with the grow
Hypha logs each block from inoculation to harvest, with every flush's weight, so the figures these calculators ask for are there when a block finishes.
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