Fermentation Timeline Calculator
Enter your yeast strain, starting gravity, and fermentation temperature to see predicted final gravity, ABV, a day-by-day gravity curve, and the best window for dry-hop or other additions. Nothing uploaded.
Yeast & gravity
Daily gravity curve
Learn more: predicting fermentation length and dry-hop timing
How temperature changes the estimate
Each yeast strain has an optimal temperature band and a baseline fermentation length at the middle of that band. For Safale US-05 the band is 65 to 69 F, the midpoint is 67 F and the baseline is 7 days.
Above the midpoint, each degree takes 2% off the baseline time, down to a minimum of half. Below it, each degree adds 3%, up to a maximum of 2.5 times. At 75 F, the top of US-05's range, that gives 5.9 days. At 59 F, the bottom of its range, it gives 8.7 days.
Temperature also moves the attenuation, the share of sugar the yeast eats. It rises in a straight line from the strain's minimum at the bottom of the optimal band to its maximum at the top. For US-05 that is 78% at 65 F and 82% at 69 F.
A worked example
A 1.050 original gravity beer with US-05 at 67 F gets 80% attenuation, so the final gravity is 1.010. The ABV is (1.050 - 1.010) x 131.25, or 5.25%.
The dry-hop window
The calculator builds a gravity curve over the fermentation and marks the dry-hop window from the point where gravity has fallen 50% of the way to final gravity until it is 85% of the way there. For the example above, that is days 3 to 5 of a 7-day fermentation.
Brulosophy's article on dry-hop timing says you might lose some hop aroma to CO2 scrubbing while fermentation is still bubbling. It also says early dry hopping aims for biotransformation, where yeast and hop oils interact to give a new hop flavor, and it reports more hop-derived esters and polyfunctional thiols from early additions and more monoterpene alcohols from late ones.
FAQ
Is it always best to dry-hop as late as possible?
No. The Brulosophy article describes a trade-off between aroma lost to scrubbing and the different flavors that early additions can give. The best window depends on the profile you want.
Why are the days only an estimate?
The calculator uses strain and temperature alone. Yeast health, pitch rate and wort all change real fermentation speed, so confirm with gravity readings from a hydrometer before you act on the dates.
What happens outside a strain's listed temperature range?
The calculator shows a warning when the temperature is outside the strain's recommended range, 59 to 75 F for US-05. It says to expect off-flavors or a stalled fermentation, and the day estimate there is only a rough guide.