Mushroom Yield & Substrate Calculator
Estimate spawn requirements, expected fresh harvest, and rough revenue for gourmet mushroom grows.
For edible gourmet mushrooms (e.g., oyster, lion's mane, shiitake). This is a planning estimate, not a guarantee.
How this mushroom calculator works
If you grow mushrooms at home or on a small farm, planning your substrate and expected yield can save both time and money. This calculator turns your input values into practical numbers you can actually use before inoculation day.
The key concept behind the tool is biological efficiency (BE), which compares fresh mushroom output to dry substrate input. For example, 100% BE means 1 kg of dry substrate yields about 1 kg of fresh mushrooms over all flushes.
Input fields explained
1) Number of grow bags
Enter how many bags/blocks you plan to fruit. If you use buckets, trays, or another container system, simply count each container as one unit and adjust substrate weight to match.
2) Wet substrate per bag (kg)
This is the total hydrated substrate weight in each unit. Typical small gourmet blocks often range from 1.5 kg to 4.5 kg wet weight.
3) Substrate moisture (%)
Most hardwood-supplemented substrates are prepared around 58% to 65% moisture. Higher moisture can reduce air space and invite contamination; too low can limit production.
4) Spawn rate (%)
Spawn rate influences colonization speed. Faster colonization usually means lower contamination risk and better consistency. A common planning range is 5% to 15% of wet substrate mass.
5) Biological efficiency (BE %)
BE depends on genetics, cleanliness, substrate formula, fruiting conditions, and harvest timing. Oyster mushrooms may reach high BE under ideal conditions, while other species may be lower.
6) Number of flushes
The calculator divides total predicted yield by your selected flush count so you can estimate harvest volume per cycle. This helps with labor scheduling and sales planning.
Quick benchmark table
| Metric | Conservative | Typical | Strong |
|---|---|---|---|
| Spawn rate | 5% | 8-12% | 15% |
| Substrate moisture | 55% | 60-63% | 64-66% |
| BE for many gourmet species | 50-70% | 70-100% | 100%+ |
Practical tips for improving results
- Use clean, vigorous spawn from reliable culture lines.
- Measure moisture consistently instead of guessing by feel alone.
- Keep incubation temperatures stable to avoid stalled growth.
- Dial in fresh air exchange and humidity during fruiting.
- Harvest at the right maturity window for quality and shelf life.
Example planning scenario
Suppose you run 40 bags at 2.2 kg wet substrate each, 62% moisture, 10% spawn, and target 80% BE across two flushes. The calculator will estimate your total fresh output, per-flush yield, dry-equivalent substrate mass, and spawn needed. If you're selling fresh product, add your price per kilogram to get a rough gross-revenue projection.
Important notes
This tool provides estimates, not guarantees. Real yield can vary based on strain vigor, contamination pressure, substrate particle size, sterilization/pasteurization quality, and local environment.
Keep records for each batch. After a few cycles, replace default values with your real production averages. Your own data will always beat generalized assumptions.