Biological Efficiency & Yield

Turn a block count and species into a real yield number.

Biological efficiency (BE%) is fresh mushroom weight divided by dry substrate weight, times 100. It's the standard way growers compare yield across species, substrates, and farms — and the one number most new growers apply to the wrong weight. This tool takes your species, block count, and dry substrate weight and turns BE% into an actual fresh-yield number, split across flushes. Flip it around and enter a target harvest (say, a weekly wholesale order) and it tells you how many blocks you need to make that order, working backward from the same math.

Everything runs client-side. Nothing is stored, nothing is sent — change any input and the result updates live.

The math behind the number.

BE% is always measured against dry substrate

The definition never changes: BE% = (fresh mushroom weight ÷ dry substrate weight) × 100. "Dry substrate weight" means the bone-dry mass of sawdust, soy hulls, straw, or whatever the mushroom is actually consuming — not the wet, hydrated, finished block weight that goes into the autoclave. That distinction is the entire crux of this calculator, and of the BE number in general.

Why this tool asks for dry weight, not block weight

A finished 5 lb gourmet block isn't 5 lb of substrate — it's roughly 60% water. At 60% moisture, that 5 lb block is only about 2 lb of dry substrate. If you plug the full 5 lb into a BE calculation, you overstate every yield number by roughly 2.5×, because you've divided by a weight that includes water the mushroom never metabolized. This is the single most common BE mistake, and it's why the input here is explicitly the dry weight, with a hint reminding you what a typical hydrated block converts to.

When the standard number is wrong.

BE% is one of the most-quoted numbers in gourmet growing, and one of the most-misapplied. Here's where it quietly costs you a batch or a bad order commitment.

BE on the wet block overstates yield by ~2.5×

This is worth repeating on its own: BE is on DRY substrate weight, never the wet block. A 5 lb hydrated block is roughly 2 lb dry. Plug 5 lb into the BE math and you'll project a yield that's 2.5× too optimistic — a projection that looks great on a spreadsheet and falls apart the first time you actually weigh a harvest. If you don't know your dry weight, work it out from your masters mix ratio, not from the finished block on the scale.

BE varies enormously by species, strain, and substrate

The presets in this tool are typical planning numbers, not fixed constants. In the literature, lion's mane BE has been reported anywhere from 22% to 89%, and shiitake from 74% to over 107%, depending on strain, substrate formulation, and growing conditions. Treat every preset as a starting assumption for planning — your farm's real BE is whatever you measure across a few actual batches on your actual substrate, not a number from a chart.

Most of the crop is the first flush — plan on 1.5–2 strong flushes, not four equal ones

New growers sometimes model yield as four or five equal harvests. In practice the first flush is roughly half the total crop, the second is around 30%, and it falls off sharply after that. Plan your labor, packaging, and sales commitments around 1.5 to 2 strong flushes, and treat anything beyond that as bonus yield — not a reliable line item in a production schedule.

BE over 100% is real — but chasing it can cost you more than it earns

A BE% above 100 isn't a typo or an error state; it simply means the fresh mushroom weight exceeded the dry substrate weight, which is normal for a good oyster or shiitake run on a well-supplemented substrate. But pushing BE higher with heavy nitrogen supplementation raises contamination risk at the same time — and yield you lose to a green, trashed bag doesn't show up anywhere in a BE spreadsheet. A batch run at a slightly lower BE that all makes it to harvest often beats a "higher BE" recipe that loses a quarter of its bags to Trichoderma.