Mushroom Substrate Calculator
Plan a batch with confidence: get exact ingredient weights, the water needed to hit field capacity, and a realistic fresh-yield estimate for your recipe and container size.
A 54-quart monotub ≈ 51 L.
Typically 50–70% of container height.
Combined dry weight of all ingredients, before adding water.
Your Batch Plan
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Overview
The Mushroom Substrate Calculator turns a recipe and a container size into a precise shopping-and-mixing plan. Instead of guessing how much coco coir, sawdust, soy hulls, straw or gypsum a batch needs — and then over- or under-hydrating it — you get the exact dry weight of each ingredient, the amount of water required to reach field capacity, and a realistic estimate of the fresh mushrooms that batch can produce.
It's built for home cultivators, monotub and grow-bag growers, and small commercial producers working with gourmet or bulk-loving species. By anchoring on real bulk densities and moisture targets rather than ideal-case theory, it helps you scale a trusted recipe up or down without wasting substrate, water, or a whole grow cycle.
How It Works
- Pick a recipe. Choose a preset such as CVG, Master's Mix, straw, supplemented sawdust, plain coco coir, or a manure-based blend. Each preset carries its own ingredient ratio, moisture target, and density.
- Choose how to size the batch. Either enter your container details (how many, their volume in liters, and how full you pack them) or type a target dry substrate weight directly.
- Set output units. Switch between metric (grams / kilograms) and imperial (pounds / ounces, cups of water).
- Press Calculate. The tool shows total dry substrate, a per-ingredient breakdown, the water to add, the final hydrated weight, and an estimated yield range.
- Verify with the squeeze test. Use the water figure as a starting point, then fine-tune: properly hydrated substrate releases a few drops when squeezed hard, not a stream.
Formula Explanation
Every recipe is defined by an ingredient ratio, a field-capacity moisture content (the share of the finished substrate's weight that is water), a hydrated bulk density, and a biological-efficiency range for yield.
Hydrated volume = Containers × Volume(L) × (Fill% ÷ 100)Hydrated weight = Hydrated volume × Density(g/L)Dry weight = Hydrated weight × (1 − Moisture)
Water to add = Dry weight × Moisture ÷ (1 − Moisture)Each ingredient = Dry weight × its ratioFresh yield ≈ Dry weight × Biological Efficiency
Water is reported by weight and volume (1 g of water ≈ 1 mL). Because the water figure is derived from a moisture target, the dry weight plus the water always equals the final hydrated weight — the numbers stay internally consistent at any scale.
Practical Benefits
- No wasted materials. Buy and mix only what the batch needs, down to the gram.
- Consistent hydration. Hitting field capacity reliably is the single biggest lever on colonization speed and contamination resistance.
- Repeatable results. Scale a recipe that works from one tub to ten without re-deriving the ratios by hand.
- Realistic expectations. A grounded yield range helps you plan harvests, packaging, and sales rather than chasing best-case internet numbers.
- Faster shopping. The ingredient table doubles as a buy list before you ever open a bag.
Frequently Asked Questions
Field capacity is the point where substrate holds as much water as it can without excess pooling or dripping. Below it, the mycelium struggles and colonization stalls; above it, waterlogged pockets invite bacteria and mold. The calculator's water figure targets that sweet spot, but every material behaves slightly differently, so always confirm with a firm squeeze test before pasteurizing or sterilizing.
Yield is shown as a range based on biological efficiency — fresh mushroom weight as a percentage of dry substrate weight. Real results depend heavily on species, genetics, environment, and technique, so treat the range as a planning guide rather than a promise. Well-run grows often land in the middle of the range across two to three flushes.
No. Dry weight means the ingredients as purchased and measured dry (for example, a compressed coco coir brick or bagged sawdust), before you add hydrating water. The tool then calculates the water needed to bring that dry mass up to field capacity. If your ingredients are already damp, reduce the added water accordingly and rely on the squeeze test.
Yes — convert to liters first. Multiply US quarts by roughly 0.95, or US gallons by about 3.79, to get liters. As a quick reference, a common 54-quart monotub is about 51 L and a 6-quart shoebox is about 5.7 L. Enter that liter figure in the volume field.
Disclaimer: This calculator provides general planning estimates based on typical substrate densities, moisture targets, and biological-efficiency ranges. Actual ingredient needs, hydration, and yields vary with species, genetics, materials, equipment, and growing conditions. Results are for informational purposes only and are not a guarantee of outcomes. Always follow safe, lawful cultivation practices and proper sterilization or pasteurization procedures for your region and species.
