Homebrew Calculator: ABV, IBU, OG/FG, SRM and Priming Sugar
Free brewing calculators in metric or US units: alcohol by volume from your hydrometer readings, a full recipe estimate (OG, FG, ABV, IBU by Tinseth, colour by Morey) and bottle priming sugar.
1. ABV from OG and FG
ABV:
2. Recipe: OG, FG, ABV, IBU, colour
3. Bottle priming sugar
The same formulas, plus:
- 10 fermentable and 8 hop slots with a 30-malt / 20-hop library you can extend
- BU:GU ratio, °Plato and EBC
- a batch log for measured gravities, dates and tasting notes
- works offline in Excel, Google Sheets and LibreOffice
Frequently asked questions
How do you calculate ABV from gravity readings?
The standard homebrew formula is ABV = (OG − FG) × 131.25. For example, OG 1.050 and FG 1.010 gives (0.040) × 131.25 = 5.25% ABV.
How is IBU calculated?
This calculator uses the Tinseth formula: utilization = 1.65 × 0.000125^(boil gravity − 1) × (1 − e^(−0.04 × minutes)) / 4.15, and IBU = utilization × alpha acid % × hop ounces × 7490 / gallons. Boil gravity is approximated by the original gravity.
How much priming sugar do I need?
It depends on the beer volume, the highest temperature the beer reached after fermentation (which sets how much CO2 is still dissolved) and your target carbonation. The calculator uses residual CO2 = 3.0378 − 0.050062·T + 0.00026555·T² (T in °F) and 15.195 g of dextrose per US gallon per volume of CO2 to add.
How many volumes of CO2 should I target?
Typical ranges: British ales 1.5–2.0, American ales 2.2–2.7, lagers 2.4–2.7, wheat and Belgian styles 3.0–4.0. Standard bottles should not exceed about 3.0 volumes.
Can I use table sugar instead of corn sugar?
Yes. Sucrose ferments slightly more per gram, so you need about 91% of the dextrose weight. Dry malt extract needs roughly 1.47 times the dextrose weight.
Sources
- Glenn Tinseth: hop utilization (IBU) formula
- Brewer's Friend: beer colour (Morey equation)
- Brewer's Friend: how to determine ABV
- Brewer's Friend: priming calculator (residual CO2)
- BYO: grain characteristics
Estimates for hobby use; results depend on your equipment, ingredients and process. Over-carbonated bottles can burst: make sure fermentation is finished (stable gravity for 3 days) before bottling. Malt values are typical figures; prefer your maltster's spec sheet.