Mushroom substrate, capacity, and yield calculator

Plan the full chain for a block farm: raw materials and water for any block weight, how many blocks your sterilizer can actually turn out, the floor area incubation and fruiting will need, the labor it takes, and the yield range to expect. Everything runs in your browser.

1. Block and formulation

Per block

Dry matter—
Dry ingredients as purchased—
Water to add—
Grain spawn—
Substrate cost—

2. Substrate recipe

Shares are percentages of dry matter and must total 100%. Moisture is what the ingredient already contains when it arrives.

Ingredient % of dry matter Moisture (%) Bag weight (lb) Cost / bag Per block Per week Bags / week Cost / week

3. Sterilizing / pasteurizing throughput

Output

Cycles per day—
Blocks per production day—
Blocks per week—
Blocks per year—
Labor hours per week—

4. Incubation and fruiting space

Space required

Blocks in incubation—
Incubation racks / area—
Blocks in fruiting—
Fruiting racks / area—
Total grow area—
Inoculation to first harvest—

5. Yield and returns

Expected yield

Yield per block—
Saleable blocks per week—
Yield per week—
Yield per year—
Revenue per week—
Substrate cost per lb—

Weekly materials summary

Total dry ingredients as purchased—
Water to add—
Grain spawn—
Substrate cost—

Bag counts in the recipe table are rounded up, since you cannot buy part of a bag. Costs use exact weight, so a week's cost will read slightly below the cost of the bags you actually order.

How it works

  1. Formulate on dry matter, not wet weight

    Dry matter per block = block weight × (1 − moisture content)

    Recipes like Masters Mix are ratios of dry ingredients, so the split has to be applied to the dry fraction. A 5 lb block at 62% moisture carries 1.9 lb of dry matter regardless of what it is made from.

  2. Account for moisture already in the bag

    As-purchased weight = dry matter needed ÷ (1 − ingredient moisture)

    Pellets and sawdust arrive at roughly 8–10% moisture. That water counts toward your target, so water to add is the block weight minus the as-purchased ingredient weight — not the block weight times the moisture percentage.

  3. Throughput is set by the vessel, not the mixer

    Blocks per day = floor(operating hours ÷ cycle hours) × blocks per load

    Count the whole cycle: come-up to temperature, hold, and cool-down before the vessel can be opened. Partial cycles are floored, because a run that does not finish sterilizes nothing.

  4. Size rooms on resident blocks, not daily output

    Blocks in the room = (blocks per week ÷ 7) × days in the room

    A block made on Friday still occupies a shelf on Sunday. Sizing on the production-day rate instead of the weekly average overstates both rooms by roughly 40% on a five-day week — an expensive way to be wrong about a building.

  5. Yield from biological efficiency

    Yield per block = dry substrate weight × biological efficiency

    BE is fresh mushroom weight as a percentage of dry substrate weight, totalled across flushes. Treat the range as a range: well-run supplemented hardwood blocks commonly land between 75% and 110%, and the low end is the number to build a business plan on.

  6. Check the whole chain before spending

    A plan is only credible when materials, vessel capacity, room area, labor, and yield agree. Change block weight and watch every downstream figure move — that interaction is the thing a spreadsheet usually gets wrong.

Got a substrate cost per block? Feed it into the craft farm COGS calculator to add labor and overhead for a full unit cost, then set trade pricing with the wholesale price calculator.