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BU:GU ratio calculator: bitterness and gravity
BU:GU is IBU divided by original gravity points. At 30 IBU and OG 1.050, the calculation is 30 ÷ 50 = 0.60. Gravity units here are not ABV.
BrewMyBeer editorial · Sources checked 24 September 2026 · Calculated examples, not laboratory measurements. How we create content
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Convert specific gravity into gravity points
Subtract 1 from OG, then multiply by 1,000. An OG of 1.040 becomes 40 points; 1.080 becomes 80. Divide your estimated or measured bitterness in IBU by those points.
For example, two recipes at 30 IBU produce ratios of 0.75 at OG 1.040 and 0.375 at OG 1.080. The ratio makes their different starting extract concentrations visible.
Use it to compare recipes, then look deeper
The same ratio can describe different beers. Final gravity, roast, acidity, carbonation, hop character and serving conditions also affect the experience. BU:GU does not measure sweetness or prove a recipe tastes balanced.
Use measured IBU if available, or record which IBU model supplied the estimate. Avoid treating tiny differences between calculators as meaningful sensory differences. Compare similar recipes and keep the measurement method consistent.
Before you use the result
- Use original gravity, not final gravity.
- Do not divide IBU by the estimated ABV.
- Zero IBU gives a zero ratio; OG must be above 1.000.
A quick learning check
What happens to BU:GU if IBU doubles and OG stays unchanged?
Try a craft decision game →Sources & further reading
These references explain the methods and limitations. The worked examples and learning questions on this page are BrewMyBeer calculations, not claims of hands-on testing.