Guide
Cold fermentation yeast for 24, 48, and 72 hours
These percents are generated from this site’s own yeast model: instant yeast equals 0.05% times 12, divided by the sum of each stage’s hours times 2 to the power of (temperature minus 21.1) over 10. The anchor is TXCraig’s checkpoint, about 0.05% instant yeast for 12 hours at 70°F. The chart below is that model, not Craig’s full curve and not a lab.
Quick answer. For 48 hours at 4°C plus 2 hours at 21.1°C, this site’s yeast model estimates 0.036% instant yeast, 0.36 g per kilogram of flour. That is a model estimate, not a measured fridge. Every fridge row is below 10°C, where the model says the rate rule is only a rough guide.
What the table assumes
Each row is one fridge stage at 3, 4, or 5°C, then a warm-up of 2 hours at 21.1°C (70°F). The warm-up is 2 hours because the Serious Eats hacker-free recipe rests the dough 2 hours at room temperature after the fridge. That page does not print the room temperature. 21.1°C is the model’s anchor, not a measured kitchen.
The model warns that below about 10°C the doubling rule is only a rough guide, and that a room-temperature finish is a second stage. Every fridge cell in this table is below 10°C, so every row carries that warning. Open a row to see it on the yeast calculator. The model is not valid for sourdough. Salt, sugar, oil, and flour are not variables. The anchor sits in ordinary pizza range, roughly 55–75% water and 2–3% salt.
| Fridge | °C | Warm-up | Instant | Per kg flour | Calculator |
|---|---|---|---|---|---|
| 24 h | 3 | 2 h at 21.1°C | 0.068% | 0.68 g | Open |
| 24 h | 4 | 2 h at 21.1°C | 0.064% | 0.64 g | Open |
| 24 h | 5 | 2 h at 21.1°C | 0.061% | 0.61 g | Open |
| 48 h | 3 | 2 h at 21.1°C | 0.038% | 0.38 g | Open |
| 48 h | 4 | 2 h at 21.1°C | 0.036% | 0.36 g | Open |
| 48 h | 5 | 2 h at 21.1°C | 0.034% | 0.34 g | Open |
| 72 h | 3 | 2 h at 21.1°C | 0.027% | 0.27 g | Open |
| 72 h | 4 | 2 h at 21.1°C | 0.025% | 0.25 g | Open |
| 72 h | 5 | 2 h at 21.1°C | 0.023% | 0.23 g | Open |
At 24 hours and 5°C the model estimates 0.061% instant, 0.61 g per kilogram of flour. At 72 hours and 3°C it estimates 0.027%, 0.27 g. A warmer fridge or a longer rest lowers the percent, because the model gives the fridge a slow rate and then multiplies by the hours. Both figures include the same 2-hour warm-up. A kilogram at the 48-hour, 4°C row is 0.36 g, the same gram weight as the table.
What to do with it
Use the row closest to a thermometer in the dough, not the air if you can avoid it, then open that row if your warm-up is longer, shorter, or warmer than 2 hours at 21.1°C. The calculator accepts those two stages and will show active dry and fresh yeast for the same instant percent.
Serious Eats hacker-free keeps the dough in the refrigerator at least 8 hours and up to 72 hours, then 2 hours at room temperature. Its printed yeast is 1% instant on that recipe’s own flour. That percent is the recipe, not a row in this table, and the page does not print a fridge temperature.
King Arthur’s sourdough pizza crust refrigerates the dough 24–48 hours and then leaves it 2 hours at room temperature. That dough is leavened with starter. It does not belong in this instant-yeast table.
Questions
- Are these yeast percents measured in a refrigerator?
- No. Each figure is this site’s Q10 yeast model, the same function the yeast calculator uses. The anchor is TXCraig’s checkpoint of about 0.05% instant yeast for 12 hours at 70°F. The table is an estimate, not a lab measurement.
- Why is the warm-up 2 hours at 21.1°C?
- Serious Eats’ hacker-free recipe rests the dough 2 hours at room temperature after the fridge, and it does not print that room temperature. 21.1°C is 70°F, the model’s own anchor, not a measured kitchen. Change the warm-up in the yeast calculator if yours is different.
- Why does every row warn about the cold?
- Every fridge temperature in the table is below 10°C. The model’s own warning says the doubling-per-10°C rule is only a rough guide in the refrigerator, and that a room-temperature finish has to be entered as its own stage. The warm-up column is that second stage.
- Can I use this table for sourdough?
- No. The yeast model is not valid for sourdough. King Arthur’s sourdough pizza crust uses a starter, a 24 to 48 hour fridge rest, and 2 hours at room temperature. That schedule is on the sourdough pizza page and is not a row in this table.
- What if my fridge is not 3, 4, or 5°C?
- Open a row in the yeast calculator and type your own hours and dough temperature. The table is only the 24, 48, and 72 hour set at 3, 4, and 5°C, each with the same warm-up.
- Does 72 hours trigger the long-ferment warning?
- No. The model warns when a single stage is longer than 72 hours, because cells multiply and yeast does not scale in a straight line forever. A stage of exactly 72 hours does not trip that warning. The dough can still overproof. Watch it.
Last reviewed 1 November 2026.
Sources
The percents are this site’s Q10 model, anchored on TXCraig’s 12-hour, 70°F checkpoint. They are labelled as model estimates. Serious Eats supplies the 2-hour room-temperature rest and a separate printed yeast percent. King Arthur’s sourdough schedule is cited only to keep it out of this table.