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Sourdough Temperature Guide: DDT, Friction Factor, and Why Temp Decides Everything
Temperature is the single biggest variable in sourdough. A 4 °C swing in dough temperature can be the difference between a 4-hour bulk and an 8-hour bulk. This guide walks through Desired Dough Temperature (DDT), how to calculate the water temperature you need, and how to keep results consistent year-round.
What is Desired Dough Temperature (DDT)?
DDT is the temperature you want your dough to be after mixing. For most home sourdough, the sweet spot is 24–26 °C. Below 22 °C bulk fermentation drags and the loaf can taste flat. Above 27 °C the gluten weakens, the dough goes acidic fast, and you get an over-sour, gummy crumb.
Professional bakers hit DDT every batch by adjusting water temperature, the only variable they can change quickly. Flour and starter sit at room temperature; water is the lever.
The DDT formula (3-factor)
For hand-mixed sourdough, multiply your DDT by 3, then subtract the flour temperature, the room temperature, and the friction factor. The result is your water temperature.
Water temp = (DDT × 3) − Flour temp − Room temp − Friction factor
Example: target 25 °C, flour 22 °C, room 22 °C, hand-mix friction 1 °C → water = (25×3) − 22 − 22 − 1 = 30 °C.
For stand-mixer bakers, swap friction 1 for 4–5 (more mechanical heat). For levain-fed doughs, use a 4-factor formula adding starter temperature.
Friction factor by mixing method
- Slap-and-fold (5–8 min): +1–2 °C
- Stretch-and-fold only: 0 °C
- Wooden spoon stir-up: 0 °C
- Stand mixer, low (5 min): +3 °C
- Stand mixer, medium (5 min): +5 °C
- Spiral mixer pro (10 min): +6–8 °C
Test your friction factor once: mix a batch with the water temp you used, measure the dough after mixing, and the difference from your prediction is your true friction.
Seasonal water-temperature targets
Most home kitchens swing 6–8 °C between summer and winter. Calibrate your water by season:
- Summer kitchen (26–28 °C): water 16–18 °C — even ice water for high friction setups.
- Spring/fall (22–24 °C): water 24–28 °C — tap-cool to mildly warm.
- Winter kitchen (16–19 °C): water 32–36 °C — warm but not hot to the wrist.
Never go above 38 °C — bacterial growth in the starter slows above this temperature, and you risk killing the wild yeast at 42–45 °C.
Holding temperature during bulk
Mixing to DDT is half the battle. The other half is keeping the dough at that temperature for the next 4–6 hours. A simple proofing setup: place the dough in an off oven with the light on (most ovens hold ~26 °C this way) or in a closed insulated box with a hot water cup. A folded blanket around a cylinder works in a pinch.
For winter consistency, a $40 Brod & Taylor folding proofer set to 25 °C eliminates kitchen drift entirely.
Common temperature mistakes
- Using the same water temp year-round. Tap water swings 4–10 °C across seasons. The same recipe ferments very differently in January vs July. Use a thermometer.
- Ignoring friction from a stand mixer. A 5-minute mix in a KitchenAid adds 3–5 °C to the dough. Use cooler water than your hand-mix instinct says.
- Hot tap water "to wake the starter". Water above 38 °C harms wild yeast and lactobacilli. Warm to body temperature is plenty.
- Trusting the room thermostat. Counter temperature near a window in winter is 3–5 °C below the room thermostat reading. Measure where the dough actually sits.
Temperature troubleshooting
- Dough finishes mixing at 28 °C+. Either water was too warm or friction was higher than expected. Use ice water to drop 2–3 °C, or place the dough in the fridge for 20 minutes after mixing.
- Dough finishes at 21 °C in winter. Bulk will run 8–10 hours. Either accept the longer schedule or use the oven-light proofer trick to hold 25 °C.
- Crumb is gummy and over-sour. Bulk ran too warm. Drop DDT by 2 °C next bake (cooler water).
- Loaf is dense and bland. Bulk ran too cold and never finished. Either extend bulk or warm the dough.
Skip the math: the main calculator includes a DDT solver — enter your kitchen temperature and it outputs the water temperature for a 25 °C dough.
Temperature FAQ
24–26 °C is the sweet spot for most home recipes. Pizza doughs run cooler (22–24 °C) for slow flavor development; rye and whole grain run warmer (26–28 °C) to compensate for slower gas production.
Yes — even ice water is fine if your kitchen is 28 °C. The DDT formula will tell you exactly how cold.
Yes, especially with high inoculation (20 %+). For levain doughs, use the 4-factor formula adding levain temperature.
A $10 instant-read with ±1 °C accuracy is plenty. Avoid alcohol thermometers (slow and imprecise).
Yes, by exactly the temperature differential. Flour from a winter pantry can be 3–5 °C below the kitchen — measure it.
Bulk fermentation will be inconsistent — sometimes 4 hours, sometimes 9. The dough still tells you when it is ready, but planning becomes guesswork.
Related guides
Disclaimer: Baking results vary based on flour type, ambient temperature, starter health, and technique. Use this guide and our sourdough hydration calculator as a starting point, then adjust to your conditions.