Free tool
Oyster mushroom substrate calculator: how many blocks for X kg?
Before starting a production run, two questions almost always get answered by gut feel: how many blocks to prep, and how much substrate that means. Here's the exact formula, not a rough guess — the same one MycoFlow uses for its launch suggestions.
The calculator
Weigh one of your own blocks for a reliable estimate. The default (15 kg) matches a pasteurized straw substrate bag for a small farm — a ready-to-fruit block bought from a supplier is often much lighter (2 to 5 kg).
Blocks to start
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Total substrate
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Math: substrate weight per block × yield gives the expected harvest per block; target weight divided by that number, rounded up to the next whole block, gives the block count. Substrate weight per block has no universal value — that's the trap: using a reference number instead of your own can throw off the estimate by a factor of 2 or 3.
What is biological efficiency (yield)?
In oyster mushroom cultivation, yield — or biological efficiency (BE) — is the weight of fresh mushrooms harvested relative to the dry substrate weight used, expressed as a percentage. A 20% BE on a 15 kg block yields 3 kg of oyster mushrooms harvested across all flushes.
It's the central number in this calculation: it depends on your strain, substrate quality, fruiting-room climate and accumulated experience — there's no universal value, only reference ranges (often 15–30% for a small-scale oyster mushroom operation, higher under optimized conditions).
Why yield drops on the second flush
A single substrate block produces several successive harvest waves — flushes. Each one draws on the block's nutrient reserves, already depleted by the previous flush: the first flush is almost always the most generous (often 50–60% of total yield), the second noticeably smaller, a third smaller still if you keep it going.
This is normal, not a sign of a problem — as long as the drop stays gradual and consistent from one cycle to the next. A sharp drop or a near-empty flush points instead to contamination or a poorly prepared substrate.
Beyond a one-off calculation
This calculator gives a snapshot estimate from a yield number you enter. The real work — and it's what MycoFlow does continuously — is tracking your actually observed yield, flush by flush, batch after batch, to refine that estimate over time instead of guessing it again for every order. No AI, no opaque predictions — the same deterministic calculation, fed by your own harvest data.
Note: MycoFlow's interface is French-only today. This page and the waitlist below are how we're gauging interest in an English version — see the FAQ on the main page for details.
Production tracking by flush, substrate needs calculation, stock and traceability — one tool, built with a real farm.
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