BU/GU is SO important to know something about for a balanced beer. The higher the gravity is, the higher the bitterness needs to be - relatively. It also depended on the style. 

In beer brewing, BU (Bitterness Units) and GU (Gravity Units) are two essential metrics for understanding the balance of flavor between bitterness and sweetness in beer. This guide provides an overview of how these relate and influence the beer’s profile.

Understanding BU and GU:

BU (Bitterness Units): Also known as International Bitterness Units (IBUs), this measures the bitterness imparted by hops. Higher BUs indicate a more bitter beer, typically ranging from 0 to 100+ depending on the style.

GU (Gravity Units): Represents the sugar content in the wort before fermentation, also known as Original Gravity (OG). The value is derived from the specific gravity reading (e.g., an OG of 1.050 is 50 GU).
BU/GU Ratio:

The BU/GU ratio is a simple calculation to understand the balance of bitterness (hops) and sweetness (malt).

Formula: BU/GU ratio = BUs / GUs.

Example: If a beer has 30 IBUs and an OG of 1.050 (50 GU), the ratio is 30 / 50 = 0.6.

Interpreting the Ratio:

Balanced Beer (0.5-0.8): Offers a good mix of bitterness and malt sweetness.

Malt-Forward Beer (<0.5): Typically sweeter and less bitter, common in malt-heavy styles like barleywines.

Hop-Forward Beer (>0.8): More bitter, usually found in hop-focused styles like IPAs.

Application:

Use the BU/GU ratio during recipe formulation to predict the taste profile of the finished beer.
Adjust the ratio according to the desired style by changing hop addition timings, quantities, and grain bill.

Experimentation:

Experiment with various BU/GU ratios across different styles to find your ideal taste balance.
Remember that other factors like yeast selection and water chemistry can also influence the final taste.
By understanding and controlling the BU/GU ratio, you can effectively design beers that suit specific taste profiles, whether you prefer a balanced, malt-forward, or hop-forward beer.