Mushroom yield calculator
Enter your harvest weight and substrate weight to get your biological efficiency, with a wet-weight option.
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Enter your weights and press Calculate.
How the math works
Biological efficiency, or BE, is the weight of fresh mushrooms divided by the dry weight of the substrate, times 100. A journal article on oyster mushrooms states it that way, citing Chang and Miles. Rootlab, a kit seller, puts it plainly: 100% BE means 1 kg of fresh mushrooms from 1 kg of dry substrate, over multiple flushes.
If you only know the wet weight of a block, the calculator turns it into dry weight by taking off the water share: dry weight equals wet weight times (1 minus the water share). Rootlab's own example is a 2.3 kg block made of 900 g of dry substrate and 1.4 kg of water, and a 900 g harvest from it is a BE of 100%. Using the wet weight by mistake would make the number look much lower than it is.
One seller's ranges, for context
Rootlab lists approximate BE ranges for its strains: blue oyster 100 to 200%, king oyster 100 to 150%, lion's mane 90 to 140% and reishi 80 to 120%. These are one seller's estimates for its own products, not a standard, and your result will depend on your substrate, your conditions and how many flushes you count.
Using it with a boxed kit
Boxed kits list a block weight that includes water, so you need the water share to find the dry weight, and the seller may not state it. If you only want to know whether a kit paid for itself, the grow-your-own vs store cost calculator is simpler. For the growing method, see how to grow mushrooms at home.
Related pages
Common questions
What is biological efficiency in mushroom growing?
It is the weight of fresh mushrooms divided by the dry weight of the substrate, times 100. Rootlab says 100% means 1 kg of fresh mushrooms from 1 kg of dry substrate over multiple flushes.
How do I get the dry weight of my substrate?
If you know the wet weight and the water share, multiply the wet weight by (1 minus the water share). Rootlab's example is a 2.3 kg block with 900 g of dry substrate and 1.4 kg of water.
Does biological efficiency count every flush?
Rootlab's definition is over multiple flushes, so add up every harvest. If the block is still producing, your number is a running total.
Is 100% a good result?
Rootlab lists approximate ranges by strain, from 80 to 120% for reishi up to 100 to 200% for blue oyster. They are one seller's estimates, so treat them as context and not a target.
Sources
- Maximising Your Mushroom Yield: Estimated Biological Efficiency of Various Mushroom Strains, Rootlab. Checked November 11, 2026.
- Production efficiency of oyster mushroom on saw dust, wood chips and wheat substrates, Indian Journal of Horticulture. Checked November 11, 2026.
How this page is checked
Cedrick Reese built this calculator on the standard biological efficiency formula, which a journal article and a kit seller both state the same way, and checked it against the seller's worked example of 900 g from 900 g of dry substrate. The page does not predict a yield, because the ranges it mentions are one seller's estimates. Everything else is arithmetic on your own numbers.