Sourdough Overnight Schedule Calculator

Your bake parameters

Target bake time (what time should the bread come out?) Dough temperature (bulk fermentation environment)

Cold retard duration (hours in fridge) Starter activity level High — peaks within 4–5 hours (fed <12h ago, very bubbly) Medium — peaks in 6–8 hours (fed yesterday, active) Low — peaks in 10–12 hours (fed 2+ days ago, sluggish) Starter hydration 100% (equal weight flour and water — most common) 80% (stiffer levain) 125% (wetter levain) Oven preheat time (minutes)

Your schedule

How it works

This calculator reverse-engineers your entire baking day from a single anchor point: the time you want bread on the table. Every stage is back-calculated using fixed durations — except bulk fermentation, which uses Q10 temperature correction to account for how yeast speed changes with dough temperature.

Q10 temperature correction

Yeast fermentation roughly doubles in speed for every 10°C (18°F) rise in temperature — a ratio called Q10 ≈ 2.0. The calculator uses 24°C (75°F) as a reference temperature with a 4-hour baseline bulk ferment (at 80% hydration, medium-activity starter). The adjusted bulk time is:

Example: At 78°F (25.6°C) with a medium starter, multiplier = 2^((25.6 − 24) ÷ 10) ≈ 1.11. Adjusted bulk = 4h ÷ 1.11 ≈ 3h 36min. At a cooler 68°F (20°C), multiplier ≈ 0.76, so bulk ≈ 5h 16min.

Stage durations (fixed defaults)

Frequently asked questions

What is a cold retard and why does it matter for scheduling?

Cold retarding means placing your shaped loaf (in a banneton or covered bowl) in the refrigerator overnight, typically between 4°C and 6°C (39–43°F). At that temperature, yeast activity slows to nearly zero, so fermentation pauses while lactic acid bacteria continue to work. This develops deeper flavor and lets you bake on your own schedule the next morning. Because fridge temperature is standardized, the cold retard window is flexible — anywhere from 4 to 24 hours works well, which is why this calculator lets you set it. The key scheduling constraint is everything that happens before it: bulk fermentation, which is highly temperature-sensitive and must happen at room temperature.

How does dough temperature affect bulk fermentation time?

Yeast metabolism speeds up significantly as temperature rises — roughly doubling for every 10°C increase (the Q10 principle). This means a dough at 80°F (27°C) will complete bulk fermentation in roughly half the time of a dough at 70°F (21°C). Small temperature differences matter a lot: even 2–3°F can shift your bulk by 20–30 minutes. This is why measuring dough temperature with a probe thermometer — not just ambient room temperature — gives you the most accurate schedule. This calculator uses your dough temperature as the primary driver for bulk fermentation time.

Do I have to take the dough out of the fridge before baking?

You do not need to temper (warm up) a cold-retarded loaf before baking — in fact, most experienced bakers score and load the dough directly from the fridge while it is still cold and firm. This makes scoring cleaner and helps the loaf hold its shape going into a hot oven. The calculator schedules removing the dough from the fridge at the same moment the oven preheat begins, so both are ready together. If your oven takes longer than 45 minutes to reach temperature (particularly with a Dutch oven), increase the preheat time input.

Why is levain build time separate from starter activity?

The levain (a small portion of fed starter) needs time to peak — to reach maximum leavening power — before you mix it into your dough. How long that takes depends almost entirely on your starter's current activity level and the ambient temperature. A very active starter fed that morning in a warm kitchen may peak in 4–5 hours; a starter that has been in the fridge for several days may take 10–12 hours to rebuild strength. This calculator maps starter activity (High / Medium / Low) to levain peak times and back-calculates when you need to build your levain. If your levain is already built and peaked, you can skip that stage and use the bulk ferment start time as your anchor.

My bulk fermentation is running faster or slower than the schedule — what should I adjust?

Temperature is the most common culprit. If bulk is moving faster than expected, your dough is warmer than you entered — friction from mixing and a warm spot in the kitchen both contribute. If bulk is slow, your dough is cooler. Trust the dough over the clock: look for 50–75% volume increase, a domed top, visible bubbles, and a jiggly texture when you shake the container. You can adjust on the fly by moving the dough to a warmer or cooler spot. For future bakes, a more accurate dough temperature reading (taken with a probe thermometer immediately after mixing) will tighten the schedule.