Free Mushroom Substrate Calculator: CVG & Monotub Ratio Tool

Mushroom Cultivation Dashboard

Calculate precise substrate recipes, spawn ratios, and harvest yields

Tip: A standard 54-quart Monotub container filled 3 inches deep requires roughly 12 to 14 quarts of total mixed material.
Higher grain spawn ratios colonize your bulk tub rapidly, outrunning mold vectors.
Required Material Recipe
4.0 Quarts
Grain Spawn Inoculum Needed

COCO COIR BASE:
8.0 Quarts
VERMICULITE:
1.6 Quarts
GYPSUM STABILIZER:
0.5 Cups
Hydration Note: Bring bulk ingredients up to “Field Capacity” (hydrated so only a few drops release when hard squeezed).

Why Use a Mushroom Substrate Calculator?

  • Growing gourmet mushrooms at home requires shifting away from expensive pre-made blocks to bulk mixing.

Our free mushroom calculator eliminates the guesswork, helping you prepare perfectly balanced growing mediums that colonize rapidly while minimizing the risk of contamination.

The Ultimate CVG Substrate Calculator Recipe

For the vast majority of indoor growers, the gold standard growing medium is a blend of Coco Coir, Vermiculite, and Gypsum (known as CVG). Using a precise

cvg substrate calculator ratio ensures your mix achieves perfect water retention and structural aeration:

Coco Coir: Provides the carbon-rich organic matrix structure that mushroom mycelium loves to digest.

Vermiculite: A naturally occurring mineral that acts like a sponge, locking in vital moisture so your bulk tub doesn't dry out during the intense first flush.

Gypsum: Introduces essential calcium and sulfur minerals while stabilizing the overall pH levels of your organic matter.

Achieving Field Capacity

When using our vermiculite coco coir bulk substrate calculator, remember that hydration is everything. Your final mixed CVG should reach "field capacity."

To test this, grab a handful of the mixed substrate and squeeze it firmly. Only a few stray drops of water should escape between your knuckles. If it streams out, it is too wet; if no drops appear, it is too dry.

Mastering the Monotub Substrate Calculator Layout

A monotub is simply a modified plastic storage tote used to mimic ideal fruiting environments. When using a monotub substrate calculator, the primary objective is ensuring your mixed substrate settles at an optimal depth inside the tub—ideally between 3 to 4 inches.