Home Brewing
ABV, IBU, grain bill and priming sugar tools for homebrewers.
ABV Calculator (OG → FG + Refractometer)
Calculate beer ABV from original and final gravity, with refractometer correction and attenuation %.
IBU Hop Bitterness Calculator (Tinseth & Rager)
Calculate IBUs from boil time, gravity, hop AA% and batch size using Tinseth or Rager utilisation.
Grain Bill, Mash & Strike Water Calculator
Plan a beer recipe: fermentables percentages, predicted OG, SRM colour, mash and strike water volumes.
Priming Sugar Calculator (Bottle Carbonation)
Grams of priming sugar for target CO₂ volumes by style, batch size and temperature.
What these tools are for
Brewing calculations are where a small measurement error compounds into a finished beer you did not intend. ABV comes from the difference between two gravity readings, so an error in either one is doubled in the result — and both readings need temperature correction unless your hydrometer happens to be calibrated to the temperature you took them at.
Bitterness is more approximate than its precision suggests. IBU formulas (Tinseth, Rager and others) model isomerisation from alpha acid, boil time and gravity, but real utilisation varies with vigour of boil, hop form and even kettle geometry. Two brewers following the same recipe can land 15% apart and both be right.
Priming sugar is the one to get exactly right, because the failure mode is not a disappointing beer, it is glass. Residual CO2 depends on the highest temperature the beer reached after fermentation, not its current temperature — a detail that is easy to miss and expensive to get wrong.
Which one do I want?
- Working out final ABV
- ABV from OG and FG.
- Bottling a batch
- Priming sugar — and use the peak post-fermentation temperature.
- Designing a recipe
- Grain bill and IBU calculator.