Two batches of the same dough, mixed with the same weights and the same starter, can finish bulk fermentation hours apart. The usual reason is temperature. Yeast and the bacteria in a sourdough culture work faster when warm and slower when cool, so a few degrees can move a schedule by an hour or more. Recipe timings quietly assume a particular dough temperature; hit it and the timings mean something. Desired dough temperature (DDT) is the method bakers use to get there, and it comes down to choosing the right water temperature.
What temperature should dough be?
For most lean yeasted doughs and sourdoughs, a DDT of 75–78°F (24–26°C) is a good target: warm enough for steady fermentation, cool enough that the dough doesn't race ahead of its gluten development or turn overly sour. Doughs headed for a long cold retard are often mixed a little cooler, and butter-rich doughs such as brioche are kept cool so the butter stays in the dough instead of melting out. Whatever your target, the point of DDT is consistency: the same dough temperature every time gives you the same timeline every time.
The DDT formula
A freshly mixed dough ends up at roughly the average temperature of everything that went into it, plus the heat added by mixing. Water is the easiest ingredient to warm or cool, so bakers solve for water:
water temperature = DDT × 3 − (flour temperature + room temperature + friction factor)
The 3 is the number of temperatures being averaged: flour, room and water. When the dough includes a preferment such as a sourdough levain, poolish or biga, that becomes a fourth temperature. The multiplier becomes 4 and the preferment's temperature joins the subtraction:
water temperature = DDT × 4 − (flour + room + preferment + friction factor)
Use one unit throughout. Measure the flour with a probe thermometer pushed into the bag or bin, the room near your work surface and the preferment just before mixing.
The friction factor
Mixing warms dough. The friction factor is the allowance for that heat, and it depends mostly on how hard and how long the dough is worked. These are the presets the LoafCalc calculator uses:
| Mixing method | Friction factor (°F) | Friction factor (°C) |
|---|---|---|
| Stretch-and-folds or no-knead | 2°F | 1°C |
| Hand kneading | 7°F | 4°C |
| Stand mixer | 24°F | 13°C |
A friction factor is a temperature difference, not a temperature reading, so convert it between scales by dividing or multiplying by 1.8 with no 32° offset: 24°F ÷ 1.8 = 13.3°C, and 7°F ÷ 1.8 = 3.9°C. Running it through the usual thermometer formula, (24 − 32) ÷ 1.8, would give −4.4°C, which is meaningless here and would have you reaching for far colder water than you need.
How to measure your own friction factor
The presets are starting points. Your mixer, its speed and your mixing time all change the number, so it is worth measuring:
- Before mixing, record the flour, room and water temperatures, plus the preferment's if you use one.
- Mix exactly as you normally do.
- Measure the dough temperature as soon as mixing ends.
- Calculate
friction = dough temperature × 3 − (flour + room + water), using × 4 and including the preferment if there was one.
Example: flour 68°F, room 70°F, water 80°F, and the dough measures 80°F straight out of the stand mixer. 80 × 3 − (68 + 70 + 80) = 240 − 218 = 22°F, or about 12°C. Repeat over a few bakes and average the results. The friction factor in this formula is a bookkeeping number that makes the arithmetic work rather than the literal rise you would see on a thermometer, which is why it has to be measured with the same formula you use it in.
Worked examples
Celsius: hand-kneaded yeasted dough
DDT 24°C, flour 18°C, room 20°C, hand kneading 4°C:
24 × 3 − (18 + 20 + 4) = 72 − 42 = 30°C
Use water at 30°C (86°F): comfortably warm to the touch and well within the safe range for yeast.
Fahrenheit: sourdough with a levain
DDT 78°F, flour 70°F, room 72°F, ripe levain 75°F, stretch-and-folds 2°F:
78 × 4 − (70 + 72 + 75 + 2) = 312 − 219 = 93°F
Water at 93°F (about 34°C) brings this country sourdough to 78°F. Because the dough is barely worked, almost all the warmth has to come from the ingredients, which is why no-knead and stretch-and-fold doughs often call for surprisingly warm water.
Fahrenheit: a cool kitchen, kneaded by hand
DDT 76°F, flour 68°F, room 70°F, hand kneading 7°F: 76 × 3 − (68 + 70 + 7) = 228 − 145 = 83°F water.
When the answer is colder than your tap
In summer, or with a stand mixer, the formula can call for water colder than any tap delivers. With a DDT of 76°F, flour at 82°F, the room at 85°F and a stand mixer (24°F): 228 − 191 = 37°F. The fix is ice, weighed as part of the recipe's water:
ice = total water × (tap temperature − needed temperature) ÷ (tap temperature + 80) in °C
ice = total water × (tap temperature − needed temperature) ÷ (tap temperature + 112) in °F
The 80 comes from the heat it takes to melt ice: melting a gram of ice absorbs about as much heat as a gram of water gives up when it cools by 80°C. In Fahrenheit that is 144°F, and subtracting the 32°F at which ice melts gives 112.
| Example | Total water | Tap | Needed | Ice | Tap water |
|---|---|---|---|---|---|
| Metric | 700 g | 15°C | 5°C | 73.7 g | 626.3 g |
| Summer kitchen above | 700 g | 65°F | 37°F | 110.7 g | 589.3 g |
For the metric row: 700 × (15 − 5) ÷ (15 + 80) = 7,000 ÷ 95 = 73.7 g of ice, plus 700 − 73.7 = 626.3 g of tap water. For the summer kitchen: 700 × (65 − 37) ÷ (65 + 112) = 19,600 ÷ 177 = 110.7 g of ice. Stir until the ice has fully melted before you mix, so the dough isn't left with lumps of ice. The formula assumes ice at its melting point; ice straight from the freezer is colder, so the water will end up slightly cooler than calculated, which is rarely a problem. Other ways to take heat out: chill the flour beforehand (and measure its new temperature), mix for less time or at a lower speed, or let bulk fermentation run somewhere cooler.
When the answer is too hot
A cold winter kitchen pushes the other way. A DDT of 78°F with flour at 60°F, the room at 62°F and stretch-and-folds (2°F) gives 234 − 124 = 110°F. The Celsius version is much the same: 26 × 3 − (16 + 17 + 1) = 44°C. Water that hot stresses commercial yeast and the microbes in a starter. Keep water at or below about 105°F (40°C) when it will touch yeast, and make up the difference elsewhere: warm the flour, mix in the warmest part of the kitchen, ferment in an oven with only the light on or in a proofing box, or accept a slower rise and give the dough more time.
Putting it into practice
- Keep an instant-read thermometer by the scale and take the four readings every time; it takes less than a minute.
- Measure the dough again at the end of mixing and write it down. If you consistently land 2°F (1°C) high or low, adjust your friction factor.
- Remember that the dough keeps changing temperature during bulk fermentation if the room is much warmer or cooler than the dough, so a warm or cool spot matters as well as the starting temperature.
The desired dough temperature calculator runs both formulas, includes the friction presets above and works out the ice automatically. If you are switching between yeast types or converting to sourdough, the yeast conversion guide explains how fermentation time changes too.