Mushroom Yield Calculator
Mushroom fresh yield from substrate and BE.
What it does
Mushrooms fruit from substrate at biological efficiency: fresh pounds per dry substrate pounds as a percent. Oysters commonly beat 100% since water joins the harvest. This page multiplies substrate by BE with first flush beside it.
The default is a 50 lb block at 100%. Yield is 50 lb fresh with 35 lb first flush. Metric converts the block to 22.7 kg and gives the same 22.7 kg with 15.9 kg first.
Efficiency is strain plus care. Fresh spawn, full colonization, steady humidity, and fair air exchange lift BE while contamination and dry spells sink it. Later flushes taper, which is why the first takes about 70%.
Basis matters most. BE divides by dry substrate in textbooks, while blocks weigh wet in kitchens. Enter matching basis or treat the percent as planning rather than audit.
How to use
- Pick imperial or metric first.
- Enter substrate weight.
- Enter BE percent.
- Read yield first, then first flush.
- Plan later flushes from the rest.
Formula
- substrate
- Substrate block weight.
- BE
- Biological efficiency percent.
Biological efficiency divides fresh mushroom weight by dry substrate weight as a percent; oysters often run 75 to 200% across flushes with about 70% first. Substrate enters as used weight here, so wet versus dry basis shifts the honest percent.
Worked example
Example: 50 lb oyster block
50 lb substrate at 100% efficiency (metric 22.7 kg).
- Yield: 50 x 100 / 100 = 50 lb.
- First flush: 50 x 0.7 = 35 lb.
- Metric: 22.7 kg gives 22.7 kg.
- Metric first: 22.7 x 0.7 = 15.9 kg.
- Tool shows 50 lb imperial and 22.7 kg metric.
Reference table
| Substrate | Yield | First |
|---|---|---|
| 10 lb | 10 lb | 7 lb |
| 20 lb | 20 lb | 14 lb |
| 50 lb | 50 lb | 35 lb |
| 100 lb | 100 lb | 70 lb |
| 100 kg | 100 kg | 70 kg |
Limits
- Planning math. Contamination excluded.
- Wet versus dry basis shifts BE.
- One BE per pass. Flushes taper.
- Strain and climate excluded.
Common mistakes
- Reading BE as guaranteed yield.
- Mixing wet with dry basis.
- Counting spawn weight as substrate.
- Forgetting later flushes taper.
- Drying the block mid fruiting.
Try it yourself
Quick checks. Answers sit tucked under each question.
20 lb at 100%?
20 lb with 14 lb first.
50 lb at 150%?
75 lb (50 x 150/100), first 52.5 lb.
Questions
Fresh yield?
Substrate times efficiency. Here 50 lb.
First flush?
Seventy percent of total. Here 35 lb.
Efficiency used?
75 to 200% for oysters; 100 is a planning middle.
What is that in metric?
22.7 kg with 15.9 kg first.
Guaranteed?
No. Contamination and dry air cut real harvests.
Spawn included?
No. Spawn, supplements, and soak sit outside BE math.