Mushroom Yield Estimator

Biological efficiency is the standard way growers measure substrate productivity: fresh mushroom weight harvested divided by the DRY weight of the substrate, times 100. The formula is BE% = (fresh harvest weight / dry substrate weight) x 100. A 60% BE on 10 kg of dry straw means 6 kg of fresh mushrooms. BE is always computed on dry substrate weight - computing it on wet weight is the most common source of inflated numbers you see online.

Multiply your dry substrate weight by the biological efficiency of your species and substrate. For example, 10 kg of dry straw inoculated with oyster mushrooms at a conservative 60% BE gives about 6 kg of fresh mushrooms. This calculator defaults to the low (conservative) end of each published BE range, because first-time grows rarely hit optimized numbers. Switch to "experienced / optimized" only if your setup, strain, and supplementation genuinely warrant it.

A typical 5 lb (2.5 kg) oyster grow kit on master's mix holds roughly 1 kg of dry substrate. At a conservative 70% BE that is about 0.7 kg (1.5 lb) of fresh oysters; a well-run block can reach 1.4 kg (3 lb) at 140% BE. Most of it arrives in the first flush. Enter your own block weight in the calculator above to get a flush-by-flush projection.

Most gourmet species give 2 to 3 productive flushes from one substrate block. The first flush is the largest (roughly 60% of the block's total potential), the second about 28%, and a third about 12% - a decay pattern driven by nutrient depletion and the block drying out. Some growers stop after flush 2 because the extra wait and contamination risk of flush 3 rarely pay off. The calculator models exactly this 60/28/12 decay and lets you choose 1, 2, or 3 flushes.

Each flush consumes the substrate's readily available nutrients and water, so there is simply less fuel left for the next round. The mycelium also ages, and each soak or misting between flushes raises contamination odds. Expect roughly a 40-50% drop per flush: flush 2 is typically a little under half of flush 1, and flush 3 a little under half of flush 2. That is the decay factor built into this tool.

The biggest lever is substrate nutrition: supplemented sawdust and 50/50 hardwood-soy-hull "master's mix" routinely out-yield plain straw or plain sawdust by 30-50%. Next is moisture - hydrated to field capacity (a few drops when squeezed hard), then correct fresh-air exchange, species-appropriate temperature, harvesting before caps fully open, and a vigorous commercial strain. Keep contamination out: one green-mold block at 0% drags your average yield down more than any optimization can recover.

Roughly 10 to 1. Fresh gourmet mushrooms are about 85-92% water, so 1 kg of fresh mushrooms dries down to about 90-120 g of dried mushrooms depending on the species. Shiitake and lion's mane retain a bit more dry matter (~11-12%), while button and enoki retain less (~9%). The converter above uses per-species dry-matter values from the tool's dataset.

About 100 g on average - 90 g for button or enoki, up to 120 g for lion's mane or king oyster. Reversed: 100 g of dried oyster mushrooms came from roughly 1 kg of fresh harvest. Use the fresh-dried converter section above for exact species figures.

A standard shiitake log (about 1 m long, 12 cm diameter) weighs roughly 11.3 kg wet, or about 6.8 kg of dry wood. At the typical log BE range of 10-25%, expect 0.7 to 1.7 kg of fresh shiitake over the log's whole productive life (usually 2-3 fruiting years), split across many small flushes. Logs are the slowest but lowest-effort way to grow shiitake.

A 10 lb (4.5 kg) lion's mane fruiting block on master's mix contains about 1.8 kg of dry substrate. At the conservative 60% BE that is roughly 1.1 kg (2.4 lb) of fresh lion's mane, with well-run blocks reaching about 1.8 kg (4 lb) at 100% BE. Lion's mane prefers master's mix or supplemented hardwood sawdust - plain straw performs poorly for it.

It is an honest planning estimate, not a harvest promise. Real yields swing with strain genetics, supplementation level, moisture accuracy, temperature, fresh air, and contamination - the biggest variable of all. That is why the tool defaults to the low end of published BE ranges ("honest mode"). Treat the projection as a realistic baseline for batch planning, substrate ordering, and cost math; actual results within plus or minus 30% of the estimate are completely normal.

Divide your target harvest by the BE you realistically expect: dry substrate needed = target fresh weight / BE. Want 5 kg of oyster mushrooms at a conservative 60% BE? You need 5 / 0.60 = 8.3 kg of dry straw, which is about 24 kg of wet straw at field capacity. The economics section of the tool also shows the break-even BE your batch must hit to cover its costs.

Yes - and it is not magic. BE compares FRESH mushroom weight (roughly 90% water) against DRY substrate weight, and the fruiting mushrooms pull in extra water that was never part of the dry substrate. Oyster mushrooms on well-prepared straw legitimately reach 120-150% BE. Any BE figure above 100% on a WET substrate basis, however, is either a different definition or a red flag - always check which basis a vendor or video is using.

As a rule of thumb: oyster species 60-120%, king oyster 40-80%, shiitake 40-70% on sawdust (10-25% on logs), lion's mane 40-100%, chestnut and pioppino 40-70%, maitake 20-40%, enoki 60-100%, wine cap 30-60% on outdoor beds, button 40-75% on compost. If you consistently land below 30% BE on an indoor species, check moisture at field capacity, fresh-air exchange, and contamination first.

Expected fresh yield = dry substrate weight x biological efficiency. Break it into flushes: flush 1 gets about 60% of the total, flush 2 about 28%, flush 3 about 12%. Dried yield = fresh weight x species dry-matter fraction (about 0.09-0.12). Revenue = fresh weight x price per kg; break-even yield = total batch cost / price per kg. Every one of these steps is computed live in the calculator above - no hidden math.

It can be, because the math is simple: 10 kg of dry straw costs a few dollars but can produce 6 kg of oyster mushrooms worth $60-120 at retail prices. Profitability hinges on your local price per kg and your real BE. Use the economics section: enter substrate, spawn, and other costs plus your selling price, and the tool shows revenue, profit, margin, and the minimum BE you must achieve to break even. These are planning estimates for hobby and small-farm budgeting, not financial advice.