What an aliquot jar is
An aliquot is a small sample taken from a larger batch. Right after mixing, pinch off a little dough and drop it into a small straight-sided container: a shot glass, a spice jar or a measuring cylinder. Mark the level. Because the sample ferments in the same conditions as the main dough, its rise tells you how far bulk fermentation has gone, which is hard to judge by eye in a large bowl.
Worked example. The sample starts at the 100 ml mark and now sits at 150 ml. It has risen (150 ÷ 100 − 1) × 100 = 50%. With a 75% target you are two-thirds of the way there; draw a line at 175 ml and end bulk when the dough reaches it.
The formula
Rise % = (level now ÷ starting level − 1) × 100
Mark for the target = starting level × (1 + target ÷ 100)
Any unit works as long as you use the same one for both readings, because the rise is a ratio. Height in a straight-sided jar works just as well as volume marks.
Choosing a target
There is no single right number. Recipes give targets that vary widely, and the right stopping point depends on your flour, your starter, how much starter is in the dough and especially temperature. A common approach is to note the rise at which your best loaves finished bulk and use that number next time. Change one thing at a time so the number keeps meaning something.
Tips for accurate readings
- Use a container with straight sides. In a tapered glass the level climbs faster at the narrow bottom than the dough actually grows.
- Press the sample down gently so it sits flat with no big air pockets, then mark the level.
- Keep the jar next to the main dough, not on a warmer or cooler shelf.
- Take the sample after mixing in the starter and salt, so it matches the dough.
Limits of this calculator
- It measures rise, not readiness. Check the main dough too: a domed surface, bubbles at the sides and an airy, jiggly feel.
- It does not predict how long the remaining rise will take; fermentation speeds up and slows down with temperature.