Mushroom Batch Scaling Calculator
Scale a proven grow recipe up or down and get the exact substrate, spawn, and realistic fresh & dried yield for your target number of tubs or bags.
Enter a whole number of 1 or more.
Enter substrate weight greater than 0.
Use a value from 0 to 95.
Use a realistic value from 1 to 300.
Batch estimate
Overview
The Mushroom Batch Scaling Calculator turns a single grow recipe that already works for you into a full shopping and planning list for any batch size. Instead of guessing how much bulk substrate and grain spawn a run of tubs or bags will take — and hoping the harvest lands somewhere useful — you get exact quantities and a grounded yield estimate before you commit to buying or pasteurizing anything.
It is built for hobby growers scaling from one tub to a shelf, market growers planning weekly production, and anyone selling fresh or dried mushrooms who needs to promise a harvest date with confidence. The math applies to common bulk-substrate species such as oyster, king oyster, lion's mane, and other grain-to-bulk cultures where spawn is mixed into a hydrated substrate.
How it works
- Enter the number of grow units (monotubs, bags, or trays) you plan to run.
- Enter the hydrated substrate weight a single unit holds when filled at field capacity, and pick kilograms or pounds.
- Choose your spawn ratio — how much grain spawn you mix in relative to substrate. A 1:2 ratio colonizes fast and resists contamination; 1:3 and 1:4 stretch spawn further at the cost of speed.
- Set the substrate moisture (field capacity is usually 60–70%) and your expected biological efficiency.
- Click Calculate batch. The results panel breaks down substrate, spawn, mix mass, dry weight, and both fresh and dried yield. Click Reset to clear everything.
Formula explanation
Every figure scales linearly from your per-unit recipe, then yield is anchored to the dry substrate weight — because biological efficiency is defined against dry mass, not wet mass. This is what keeps the estimate realistic instead of optimistic.
Total substrate = substrate per unit × number of units
Total spawn = total substrate × spawn ratio factor
(1:2 → 0.5, 1:3 → 0.333, 1:4 → 0.25, 1:1 → 1.0)
Dry substrate = total substrate × (1 − moisture% ÷ 100)
Fresh yield = dry substrate × (biological efficiency% ÷ 100)
Dried yield = fresh yield × 0.10
(fresh mushrooms are roughly 90% water)
Practical benefits
- Buy the right amount once. Know exactly how much coir, sawdust, or straw and how much grain spawn to prepare — no half-used bags, no mid-run shortages.
- Forecast harvests you can sell. A grounded fresh-yield number lets you quote restaurants and market stalls without over-promising.
- Plan dried inventory. The dried-weight estimate helps if you sell powders, tinctures, or packaged dried mushrooms.
- Compare spawn strategies. Toggle between 1:2 and 1:4 to see the trade-off between spawn cost and colonization speed at your batch size.
- Scale without waste. Test a recipe on one tub, then reproduce it faithfully across a whole shelf.
Frequently asked questions
Disclaimer
This calculator provides planning estimates based on the values you enter and typical cultivation assumptions. Real yields vary with species, genetics, environment, technique, and contamination. Figures are for educational and planning purposes only and are not a guarantee of results. Always follow local laws and food-safety guidance when growing, handling, or selling mushrooms.
