Hop-Engine
This calculator predicts the amount of hop bitterness for a batch of beer in international bittering units (IBU). This is based on hop schedule and the specific gravity of the boiling wort.
The boil gravity can be automatically calculated by first entering the intended original gravity for the beer followed by the total volume of the finished batch and the volume of boiling wort. Using a full volume boil technique, the boil volume will generally be slightly larger than the batch volume to account for evaporative loss. Using a partial volume boil, the boil volume will be much less than the batch volume.
In the table below, you can enter each of your hop additions, one addition per line. For each addition enter the amount of hops in ounces. Then type in the Hop Variety box to search for hop varieties or simply type the name of any hop variety you want. Hop varieties that are found will automatically enter a typical value into the alpha-acid percentage field AA (%). You can also enter an alpha-acid percentage yourself if the value is incorrect for your current batch of hops or the variety is not found.
Next enter the duration of boiling for the hop addition in minutes under Min Boiled. The hop utilization and partial IBU contribution for each hop addition is shown to the right. The sum of these partial IBU contributions is the total IBUs at the bottom. This is also shown with the original gravity and the Bitterness Units to Gravity Units ratio (BU:GU).
[x] close| Original Gravity | ||
| Batch Volume | (gallons) | |
| Boil Volume | (gallons) | |
| Boil Gravity |
| Ounces | Hop Variety | AA (%) | Min Boiled | Utilization | Partial IBU | |
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| Total IBU | = | ---- |
| Original Gravity | = | ---- |
| BU : GU | = | ---- |
Terms
Bitterness • International Bitterness Units (IBU) • Original Gravity (O.G.) • Alpha-Acid • Boil Time • Hop Utilization • BU:GU
About
This calculator predicts hop bitterness in IBUs for a batch of beer based on scheduled hop additions and specific gravity. Hops that are boiled for longer will have a higher utilization percentage, meaning more of their alpha-acids are converted into bitter compounds. The gravity of the boiled wort is also an important factor. Disolved sugars in the wort will interfere with hop utilization, and sweet flavors tend to reduce the perception of hop bitterness. This effect of bitter-sweet balance is represented by the ratio of Bitterness Units to Gravity Units (BU:GU).
This calculator uses the Tinseth Formula to estimate beer IBUs. This is based on Glen Tinseth’s empirical IBU measurements of batches brewed at his home brewery and his statistical regression of those measurements. This calculator assumes all hops are in pellet form and increases bitterness values by 10 percent above the Tinseth Formula. The orginal measurements were made using whole leaf hops which are thought to have slightly lower utilization.
There are a number other IBU formulas available that will generally predict similar values. However, they will sometimes deviate substantially given an identical set of inputs. It should be noted that the results of any formula are merely predictions and on any given set of equipment or on any given batch they could be in error of true IBUs as measured using laboratory techniques. There are a number of parameters influencing hop bitterness that are omitted from these formulas for simplicity.
The same total IBUs can be achieved using completely different hop schedules, and IBUs are only one consideration in the art of recipe formulation. IBUs provide no information on the nuances of hop flavor and different aromas which brewers can create through hop selection. Personal experience is the primary and best source of knowledge on different hop varieties and hop usage techniques. (See dry hopping and first wort hopping.) Perceptions of bitterness and the perception of balance between bitter and sweet are complicated and vary between individuals as well as being influenced by factors such as personal expectations. Fortunately, human experience is too rich and complicated to be quantified by a few numbers.
References
- Tinseth, Glenn. 1995-1999. “Glenn’s Hop Utilization Numbers.” Glenn Tinseth’s Hop Page. Retrieved 2012-11-29. http://realbeer.com/hops/research.html
- Daniels, Ray. 2000. Designing Great Beers: The Ultimate Guide to Brewing Classic Beer Styles. Boulder: Brewer's Publications.