Calculate beer bitterness ratio (BU:GU) from original gravity and IBU, or find required IBUs for a target ratio and optionally compare against your own target range.

Compare bitterness units with original-gravity points.

For example, 1.050 SG equals 50 gravity points. Enter the pre-fermentation gravity.

Optional target-range comparison

Optional. Blank means no lower-bound comparison.

Optional. Blank means no upper-bound comparison. Use a trusted recipe or style reference.

Bitterness Ratio Formula

BR = BU / GU

Variables:

  • BR is the bitterness-to-gravity ratio (BU:GU)
  • BU is the bitterness units
  • GU is the original-gravity points: (OG − 1) × 1000

To calculate Bitterness Ratio, divide the bitterness units by the gravity units.

How to Calculate Bitterness Ratio?

The following steps outline how to calculate the Bitterness Ratio.

  1. First, determine the bitterness units. 
  2. Next, determine the gravity units. 
  3. Next, gather the formula from above = BR = BU / GU.
  4. Finally, calculate the Bitterness Ratio.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Bitterness = 30 IBU

Original gravity = 1.050 SG, or 50 gravity points. BU:GU = 30 ÷ 50 = 0.6. A target ratio of 0.6 at this gravity likewise requires 30 IBU.

FAQs

What are bitterness units and how are they measured?

Bitterness units, often referred to as International Bitterness Units (IBU), are a measure of the bitterness of a beverage, such as beer, resulting from the bitterness of hops used during brewing. They are measured through a spectrophotometric method, which involves measuring the absorbance of iso-alpha acids in solution.

Why is the gravity of a liquid important in calculating its bitterness ratio?

Original gravity measures wort density before fermentation and is converted to gravity points for BU:GU. It does not directly measure final sweetness. Fermentation attenuation, ingredients and water chemistry also affect perceived balance.

Can the Bitterness Ratio formula be used for beverages other than beer?

This calculator uses the beer-brewing BU:GU convention. It is not a validated bitterness scale for tea, coffee or spirits.

How does the Bitterness Ratio affect the taste of beer?

A higher BU:GU means more IBU per original-gravity point. It does not by itself guarantee a more bitter-tasting beer. Compare recipes with appropriate style and sensory context. The optional target bounds are user-supplied, not universal style standards.