Diastatic Calculation Formulae

No doubt that you would like to use unmalted grains in many of your own recipes and concoctions, but the question always arises “how do you know it will all convert?” – as in, how do you make sure that you will have enough enzymes get all the starches to convert into sugars? In the brewing world, this must be the easiest of calculations… (Please note that these calculations have nothing to do with gelatinization, only enzymatic activity. If your starches are not gelatinized, they will not convert…period).

Degrees Lintner VS WindischKolbach Index

If you’re using continental grains from Europe, chances are the information for diastatic power will be measured in the kolbach units (symbol: WK). To convert one from the other, use the formula

Lintner = (WK+16)/3.5

Or the other way round

WK = 3.5 x Lintner – 16

To calculate the total diastatic power you can use either unit, as long as you are using the same unit.

Numbers you need for this calculation: (we will use the Cream ale recipe below as an example)

  1. Total weight of grains in your recipe
  2. Degrees Lintner / Kolbach of each of your grains.

To see if it will convert, you need to apply the following formula:

>> (Total weight of grains x unit of diastatic power per weight unit) divided by (total weight of grains in same weight unit)

If the answer to the calculation above is:

  • Less than 30 L (Lintner) or 89 WK (Windisch-Kolbach) per unit grain = your starches will convert poorly or not at all.
  • More than 30 L (Lintner) or 89 WK (Windisch-Kolbach) per unit grain = your starches should convert just fine.

EXAMPLE: Kruger Brewer’s Universal Cereal Mash Cream Ale recipe (See full recipe below)

o 2kg (4.4 lbs) 6 Row malt (Lintner = 160 )
o 1.5kg (3.3 lbs) Pale malt (Lintner = 140  )
o 1kg (2.2 lbs) Yellow corn meal (Lintner = 0 )

Total Grain weight        = 4.4lbs + 3.3lbs + 2.2lbs =  9.9lbs

Total Diastatic power    = (4.4 x 160) + (3.3 x 140) + (2.2 x 0)

= (704) + (462) + (0)

= 1166

Mash Diastatic power   = 1166 Lintner divided by 9.9lbs

= 117.7 Lintner per pound

Verdict – the mash diastatic power is higher than 30, so it has ample enzymes to convert efficiently.

Kruger Brewer’s Universal Cereal Mash Cream Ale recipe

*For the full article on cereal mashing, please follow the link HERE


  • OG: 1.050
  • FG: 1.010
  • IBU: 17
  • EBC: 8.1
  • ABV: 5.3%
  • Batch Size: 5 gallons (19 liters)
  • Estimated efficiency: 70%

o 2kg (4.4 lbs) 6 Row malt
o 1.5kg (3.3 lbs) Pale malt
o 1kg (2.2 lbs) Yellow corn meal (or any other flour, meal, etc. you feel like)
o 10g (0.35 oz) Falconer’s Flight hops ~ 60 min bittering addition – 13.5 IBU
o 10g (0.35 oz) Liberty hops ~ 30 min flavouring addition – 4 IBU
o 1 packet Safale US-05 yeast


Single Infusion at 149 °F or 65 °C for 75 minutes.

  • The amount of barley malt to remove in the recipe above for your cereal mash is 350g (about 12 oz) for Step 1..
  • The first step in this recipe is to complete the cereal mash as outlined in the article above. Once you are finished with the cereal mash boil (Step 4), you can continue to prepare your main mash as you normally would
  • Mash in your grains to get to the required temperature in a single infusion scenario. (I’m not going to outline this as we are dealing with an advanced brewing technique and all of you should be able to handle this).

While your main mash is in the mash tun at saccharification temperatures, cool your cereal mash to the same temperature – namely, 65 degrees Celsius or 149 degrees Fahrenheit – and simply add to your mash tun within the first 15 mintues of mashing. (Please see Step 5 for more info).


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