Free Tool

Substrate Calculator

Pick your recipe and batch size. We'll give you exact ingredient weights, water volume, total wet weight, and sterilization parameters.

Recipe

Number of blocks (5 lb each)

50/50 hardwood fuel pellets and soy hull pellets. The gold standard for wood-loving species.

Best for: Lion's mane, Oysters, Shiitake, King oyster, Maitake

Ingredient	Weight	(lbs)	Buy
Hardwood fuel pellets 100% hardwood, no additives	550 g	1.21 lbs	Buy →
Soy hull pellets	550 g	1.21 lbs	Buy →
Water to add	1.40 L	0.37 gal
Total wet weight	2.50 kg	5.51 lbs

Sterilization

Pressure sterilize · 250°F · 15 PSI · 150 min

Pressure sterilize at 15 PSI for 2.5 hours.

How to use this

Everything here is measured for a 5 lb (≈2.27 kg) wet block, the standard size for bag culture. Tell us how many blocks you're making and the calculator scales up every ingredient, plus water volume, plus final total weight.

Note on water: the water value is the amount to add to the dry ingredients to reach target hydration (60–65% moisture for most recipes). If your ingredients come pre-hydrated or you're working in a humid environment, adjust slightly downward.

About the recipes

These are the four standard home-grower substrate recipes: Master's Mix (the gold standard for wood-lovers), Pasteurized Straw (oysters on a budget), CVG (bulk substrate for monotubs), and Supplemented Sawdust (classic bag culture).