IBU Calculator (Tinseth Formula)
Calculate the bitterness of your homebrew hop additions
Understanding IBU in Brewing
International Bitterness Units (IBU) is a scale used to measure the concentration of iso-alpha acids in beer. These acids are derived from hops during the boiling process and provide the characteristic bitterness that balances the sweetness of the malted barley.
How the IBU Calculator Works
Our calculator uses the Tinseth Formula, widely regarded by homebrewers as the most accurate method for predicting bitterness. The calculation depends on four primary factors:
- Alpha Acid Percentage: The potential bitterness of your hop variety.
- Boil Time: Longer boils extract more bitterness (utilization).
- Boil Gravity: Higher sugar concentration (gravity) reduces hop utilization.
- Batch Size: The total volume of beer determines the concentration of the acids.
The Formula Behind the Math
The Tinseth formula is calculated as follows:
IBU = (Utilization × Weight × Alpha Acid × 7489) / (Volume × 1.34)
Utilization is further determined by the bigness factor (gravity) and the time factor (duration of the boil).
Typical IBU Ranges for Common Beer Styles
| Beer Style | Typical IBU Range |
|---|---|
| Light Lager | 8 – 12 IBU |
| American Pale Ale | 30 – 50 IBU |
| India Pale Ale (IPA) | 40 – 70 IBU |
| Imperial Stout | 50 – 90 IBU |
Pro Tips for Hop Utilization
Remember that "First Wort Hopping" or "Whirlpool Hopping" changes the utilization rate. This calculator specifically targets additions during the actual boil. If you are brewing a very high-gravity beer (like a Barleywine), you will need significantly more hops to achieve the same IBU level compared to a lighter beer like a Pilsner.