Enter the amount of spawn and substrate into the calculator to determine the Spawn to Substrate Ratio. This calculator can also evaluate any of the variables given the others are known.

Spawn To Substrate Ratio Formula

The following formula is used to calculate the Spawn to Substrate Ratio.

SSR = S / Sub

Variables:

  • SSR is the Spawn to Substrate Ratio
  • S is the amount of spawn used (in grams)
  • Sub is the amount of substrate used (in grams)

To calculate the Spawn to Substrate Ratio, divide the amount of spawn used by the amount of substrate used. This will give you the ratio of spawn to substrate. A higher ratio means faster colonization but can be more expensive, while a lower ratio is cheaper but takes longer and has a higher risk of contamination.

What is a Spawn To Substrate Ratio?

Spawn to substrate ratio refers to the proportion of mushroom spawn (the mycelium of the mushroom) to the substrate (the material the mycelium consumes) in mushroom cultivation. This ratio is crucial as it affects the speed of colonization, the yield of mushrooms, and the potential for contamination. A higher spawn to substrate ratio means faster colonization but can be more expensive, while a lower ratio is cheaper but takes longer and has a higher risk of contamination.

How to Calculate Spawn To Substrate Ratio?

The following steps outline how to calculate the Spawn To Substrate Ratio (SSR).


  1. First, determine the amount of spawn used (S) in grams.
  2. Next, determine the amount of substrate used (Sub) in grams.
  3. Next, gather the formula from above = SSR = S / Sub.
  4. Finally, calculate the Spawn To Substrate Ratio (SSR).
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Amount of spawn used (S) = 50 grams

Amount of substrate used (Sub) = 100 grams