Mushroom Growing Calculators
Free mushroom cultivation calculators: substrate volume, spawn rate, fruiting chamber humidity, grain jar ratios, and yield estimates.
Substrate, spawn, humidity and fruiting numbers. 10 calculators for gourmet growers working with oyster, shiitake, lion’s mane, king oyster, wine cap and reishi. Soilless growing sits under Hydroponics.
Spawn rate carries the mistake that ruins most first bags. The percentage is taken against hydrated substrate weight, not dry. Straw absorbs about two and a half times its own dry weight in water, so 2 kg of dry straw becomes roughly 7 kg once soaked and drained, and the rate comes off the 7. Measuring against the dry figure leaves a bag badly under-spawned, and an under-spawned bag colonizes slowly, which in practice is the same thing as a contaminated bag.
Monotub sizing works in spawn to substrate ratio by volume. 1:2 colonizes in 10 to 14 days at low contamination risk and is the right place to start. 1:4 saves spawn and takes three to four weeks, which is a long time to leave a tub open to whatever is in the room.
Oyster appears twice in the rate table with different numbers, because on straw it is quick and on sawdust the same fungus is not.
Fruiting Chamber Size Calculator
Calculate fruiting chamber dimensions for mushroom growing from substrate volume and species. Returns chamber size, FAE holes, and humidity surface area.
Grain Spawn Jar Calculator
Calculate grain spawn jars from substrate volume and spawn rate. Covers rye, wheat, oat, and corn for oyster, shiitake, and gourmet mushroom cultivation.
Monotub Substrate Calculator
Calculate substrate ratios, grain spawn amount, and tub capacity for monotub mushroom growing. Covers CVG and manure substrates, spawn ratios, and bed depth.
Mushroom Agar Recipe Calculator
Calculate agar powder, malt extract, and nutrients for mushroom media by plate count. Covers MEA, PDA, and oatmeal agar recipes with sterilization volume.
Mushroom Growing CO2 Exchange Rate Calculator
Calculate fresh air exchange rate for optimal CO2 in a mushroom fruiting chamber. Covers oyster, shiitake, and gourmet species with ppm targets by growth stage.
Mushroom Growing Humidity Calculator
Calculate humidity requirements and misting schedule for your mushroom fruiting chamber by species. Oysters need 90-95%, shiitake prefer 80-90%.
Mushroom Growing Light Cycle Calculator
Calculate optimal daily light and dark cycle for mushroom fruiting. Covers oyster, shiitake, lion mane, and reishi with recommended hours and light intensity.
Mushroom Spawn Rate Calculator
Calculate grain or sawdust spawn amount from hydrated substrate weight and target spawn rate percent. Oysters typically use 5-10%, shiitake 10-15%.
Mushroom Substrate Volume Calculator
Calculate substrate volume for mushroom growing bags, trays, or buckets from container dimensions. Returns dry weight of straw, sawdust, or grain needed.
Substrate Pasteurization Calculator
Calculate substrate pasteurization time for mushroom growing by method: boiling bath, lime, or steam. Returns hold time at 160-180°F for straw and hardwood.