What is the BU:GU ratio?

The BU:GU ratio compares IBU (Bitterness Units) to GU (Gravity Units, where GU = (OG-1) x 1000). It indicates how bitter a beer will taste relative to its malt sweetness. A ratio of 0.5 is malty, 0.8 is balanced, and 1.0+ is hoppy.

What ratio should I target?

Common targets: English Bitter 0.6-0.8, American Pale Ale 0.7-0.9, IPA 0.8-1.2, Stout 0.5-0.8, Wheat Beer 0.3-0.5, Barleywine 0.6-0.9. The ratio helps maintain balance regardless of beer strength.

Does the ratio account for real perceived bitterness?

The BU:GU ratio is a useful guideline but does not account for all factors affecting perceived bitterness. Water chemistry (chloride vs sulphate), residual sweetness (FG), carbonation level, and serving temperature all affect how bitter a beer tastes.

What about the RBR (Relative Bitterness Ratio)?

RBR is a more refined balance metric that accounts for final gravity: RBR = BU / (OE - RE), where OE is original extract and RE is real extract. It gives a better indication of perceived bitterness because it factors in residual sweetness. Values above 1.0 indicate hop-forward beers.

How does water chemistry affect perceived balance?

Sulphate-rich water accentuates hop bitterness, making the beer taste more bitter at the same IBU. Chloride-rich water enhances malt sweetness and fullness. The sulphate-to-chloride ratio is as important as IBU for perceived balance in hop-forward beers.

BrewCalcs

Bittering Ratio Calculator -- BU:GU

Calculate the BU:GU ratio to assess the balance between bitterness and malt sweetness.

IBU

International Bitterness Units of your recipe

Original Gravity

Gravity reading before fermentation (e.g. 1.050)

Final Gravity

Expected gravity after fermentation for RBR calculation

Beer Style

Select a style to check if your ratio is within the typical range

How We Calculate This

The BU:GU Ratio

BU:GU = IBU / ((OG - 1) x 1000)

GU (Gravity Units) are simply the last two digits of the OG. For example, OG 1.050 has 50 GU. If the beer has 40 IBU, the ratio is 40/50 = 0.80, indicating a balanced beer.

Relative Bitterness Ratio (RBR)

RBR = IBU / (Original Extract - Real Extract)

RBR accounts for residual sweetness via the final gravity, giving a more accurate picture of perceived bitterness.

Frequently Asked Questions

Related Calculators

IBU Calculator

Calculate International Bitterness Units using Tinseth or Rager formulas.

Hop Utilisation Calculator

Calculate IBU contribution, utilisation percentage and bittering versus flavour ratio from alpha acid, hop weight, boil time and wort gravity.

Hop Substitution Calculator

Find equivalent hop amounts when substituting varieties.

Dry Hop Calculator

Calculate dry hop amounts based on desired intensity and batch size.

First Wort Hop Calculator

Calculate IBU contribution from first wort hopping additions.

Last updated: 2025-02-20

All calculations are estimates. Always verify values and adjust based on your equipment and ingredients.