Recipe
Estimated final gravity and alcohol
A yeast with 75% attenuation on a 1.060 wort: here is where it should stop, and the strength you can announce.
Result
Fill in the values and run the calculation, or try the example.
This is the calculation Krausi uses. Create an account to save it in a recipe or a brew.
Create my accountWhy estimate the final gravity?
Every yeast consumes a share of the wort sugars, stated by the manufacturer: that is its attenuation. Knowing the expected final gravity tells you when fermentation is finished. If the recipe expects 1.015 and the hydrometer has shown 1.022 for three days, something is stuck.
It is also the way to announce the strength of a recipe before brewing it, and to choose the yeast accordingly: a more attenuative yeast gives a drier, stronger beer with the same malts.
How are the final gravity and alcohol estimated?
The final gravity follows from the original gravity and the attenuation:
FG = 1 + (OG − 1) × (1 − attenuation / 100)Alcohol is calculated with the usual formula, 131.25 × (OG − FG), as long as the original gravity does not exceed 1.070. Above that, the tool switches to the full formula, more accurate for strong beers:
ABV = 76.08 × (OG − FG) / (1.775 − OG) × FG / 0.794The result says which formula was used.
Worked example
Values entered
- Original gravity as decimal SG: 1.06
- Apparent attenuation of the yeast in %: 75
Result from the tool
- Estimated final gravity, in SG
- 1.015
- Alcohol by volume, in % ABV
- 5.91 %
- ABV formula: standard, or strong beer (OG above 1.070)
- standard
What the tool does not do
- The actual attenuation depends on the mash temperature, the amount of yeast and the temperature: the manufacturer's value is an average.
- Unfermentable sugars (lactose, crystal malts in quantity) raise the final gravity.
- It is a forecast: only the hydrometer reading is authoritative.
Frequently asked questions
My final gravity is higher than expected, is fermentation stuck?
Not necessarily. Wait two days and measure again: if the gravity is still dropping, fermentation is just slow. If it no longer moves, raise the temperature by 2 °C and rouse the yeast by gently swirling the fermenter.
Why two formulas for alcohol?
The usual formula is a linear approximation that underestimates the strength of strong beers. Above 1.070 the tool uses the full formula: for a beer at 1.090 attenuated to 80%, it gives 10.25% ABV.
And with the assistant?
Ask Krausi the same question in plain language: he picks this tool, does the calculation and files the result in your project.
My recipe aims for 1.060 with a yeast stated at 75% attenuation. Where will it finish?
It should finish at 1.015 for 5.9% ABV. I've noted these targets in the recipe: I'll let you know when your readings get close.