Garetz IBU Calculator
This page provides a calculator for predicting IBUs using the Garetz formula. This formula is described in Mark Garetz' book Using Hops. This calculator uses the simplified form of determining the hopping-rate factor, as described by Michael L. Hall in What's Your IBU? (Zymurgy Special Edition, 1997). I've changed the temperature-factor input from elevation above sea level to the boiling point of water, but the formula for the temperature factor itself remains the same. I've removed the bagging factor because previous experiments have shown this this has no effect. For the filtering factor, specify 5 microns for "soft" filtering and 1 microns for "aggressive" filtering. Finally, I've included his alpha-acid loss factor (or hop freshness factor) even though he didn't list this factor explicitly in his model of IBUs. Setting the freshness factor to 1.0 will turn off that effect.
Inputs:
Global:
| Input Units: metric or U.S. customary (e.g. gallons, ounces) | |
| Boiling Point of Water (°F): | |
Wort:
| Boil Time (minutes): | |
| Evaporation Rate (G/hr): | |
| Wort Volume (G): | pre-boil or post-boil volume |
| (Post-Boil) Original Gravity: | |
| Wort/Trub Left in Kettle (G): | (only needed for partial boils) |
| (Partial Boil) Added Water (G): |
Hops:
| Number of Hop Additions: | |
| Global IBU Scaling Factor: | |
| Default Hop Form: | |
| Specify Hop Freshness Using: | storage conditions freshness factor |
Fermentation and Conditioning:
| Yeast Flocculation: | |
| Filtering (micron rating): |
