IBU Calculator Using the SMPH Method

Frequently Asked Questions (FAQ) and documentation.


Input Units: metric or U.S.customary (e.g. gallons, ounces)
Boiling Point of Water (°F):

Kettle Diameter (inches): (for wort exposed surface area)
Kettle Opening Diameter (inches): (often same as kettle diameter)

Boil Time (minutes):
Evaporation Rate (G/hr):
Wort Volume (G @ room temp.): pre-boil or post-boil volume
(Post-Boil) Original Gravity:
Wort/Trub Left in Kettle (G):
(Partial Boil) Added Water (G):

Number of Hop Additions:
Global IBU Scaling Factor:
Default Hop Form:

Apply alpha-acid solubility-limit correction
Apply pH correction with wort pH = pre-boil or post-boil
Model IBUs of dry-hop additions (this model provides only a rough approximation)
Specify hop alpha-acid decay using: storage conditions freshness factor

Post-Boil Temperature Decrease:
Post-Boil Wort Temperature Decay Function: linear or exponential decay
   temperature (°F) = TO_BE_CHANGED

Whirlpool and/or Hop Stand Time: minutes
quickly cool to °F, then hold at this temperature during hop-stand time

Forced Cooling Method:
  immersion chiller (exponential decay factor: )
  counterflow chiller (wort flow rate: gallons/min)
  ice bath (exponential decay factor: )

Fermentation and Conditioning:
Volume at Pitching (G):
Wort Clarity into Fermentor:
Krausen Loss:
Yeast Flocculation:
Finings: tsp of
Filtering (micron rating):
Beer Age (days at room temp.):


Save and Load:

Save to File:
Load from File:


1.0.1: (2018-Nov-22 to 2021-Aug-28) Initial version.
1.0.2: (2021-Sep-04) Bug fix in AA concentration when dry hopping.
1.0.3: (2021-Oct-05) Bug fix, and don't reduce solubility limit with temperature.
1.0.4: (2021-Nov-25) Minor updates.
1.0.5: (2022-May-18) Storage duration of 0 months is valid.
1.0.6: (2022-Dec-10) Put introductory text into FAQ.
1.0.7: (2023-Jan-25) Print how long it takes to reach hold temp.
1.0.8: (2023-Jan-29) Bug fix in temp. decay, indicate max cool time.

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Copyright © 2018-2022 John-Paul Hosom, all rights reserved. All product and company names are trademarks™ or registered® trademarks of their respective holders. Use of these names does not imply any affiliation with, endorsement of, or endorsement by them.

While I hope that you find this page useful, I make no guarantees about the accuracy or suitability of the results. Predicting IBUs is a bit of a "black art", because there are so many variables and there is so much variability. The only way to really know the IBU level of a beer is to have it professionally tested, which is something I highly recommend. Cheers!