Enter the temperature of storage, humidity level, age of the hops, dry matter content, and moisture content into the calculator to determine the Hop Storage Index.

Hop Storage Index Formula

The following formula is used to calculate the Hop Storage Index.

HSI = (T * H * A) / (D * M)


  • HSI is the Hop Storage Index (%)
  • T is the temperature of storage (°C)
  • H is the humidity level (%)
  • A is the age of the hops (months)
  • D is the dry matter content (%)
  • M is the moisture content (%)

To calculate the Hop Storage Index, multiply the temperature of storage by the humidity level, then multiply the result by the age of the hops. Divide this result by the product of the dry matter content and the moisture content. The result is the Hop Storage Index, which indicates the quality of the hops over time under specific storage conditions.

What is a Hop Storage Index?

A Hop Storage Index (HSI) is a measurement used in brewing to determine the rate at which hops lose their alpha acids, the compounds responsible for the bitterness in beer. The HSI is expressed as a percentage, with higher percentages indicating a faster loss of alpha acids. This index helps brewers understand how long they can store hops without significant loss of flavor and bitterness. Factors such as temperature, packaging, and the specific variety of hop can all influence the HSI.

How to Calculate Hop Storage Index?

The following steps outline how to calculate the Hop Storage Index (HSI).

  1. First, determine the temperature of storage (T) in °C.
  2. Next, determine the humidity level (H) in %.
  3. Next, determine the age of the hops (A) in months.
  4. Next, determine the dry matter content (D) in %.
  5. Finally, determine the moisture content (M) in %.
  6. Using the formula HSI = (T * H * A) / (D * M), calculate the Hop Storage Index.
  7. After inserting the values of 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.

Temperature of storage (T) = 25°C

Humidity level (H) = 70%

Age of the hops (A) = 6 months

Dry matter content (D) = 80%

Moisture content (M) = 10%