How it works: Estimates, not exact times. Bulk time = base × 2^((24 - T) ÷ 6.75), with T the room temperature in °C and a base of about 5.5 h for 20% starter, plus 1.5 h each time the starter is halved. Starter peak time and room temperature proof (about 1.75 h at 24 °C) follow the same temperature curve, which matches common sourdough guides. The dough is assumed to be at room temperature; warmer or cooler dough moves every step. The plan works backwards from the bake time and rounds to 5 minutes.

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Planning backwards from the oven

Sourdough is slow, and the slowness is what catches people out. Feed the starter at the wrong moment and you end up shaping at midnight or baking when you should be at work. This planner starts from the moment you want the loaf in the oven and works backwards through every stage, so you can see before you begin whether the plan fits your week.

It is meant for home bakers fitting bread around work and family, and it stamps every step, from feed to bake, with a day and time.

Every time here is an estimate

Yeast and bacteria respond strongly to temperature. As a rough rule, each 7 °C of cooling doubles how long a stage needs, so a dough that finishes bulk in five and a half hours at 24 °C may need well over nine at 18 °C. The planner uses that curve, anchored to common sourdough guidance, and it adds time when you use less starter.

What it cannot see is your particular starter, your flour or the real temperature of the dough. That is why bulk fermentation is shown as a range and labelled as a guide. Treat the timeline as a plan to adjust, and let the dough have the final word: at the end of bulk it should have grown by roughly half to three quarters, feel airy, and show bubbles along the sides of the container.

Setting up your plan

Pick the day and time in When the loaf goes into the oven.
Enter Room temperature. The planner assumes your dough sits at about the same temperature.
Set Starter in the dough as a percentage of total flour. 20% is a common starting point.
Choose a Starter feed ratio. Higher ratios take longer to peak, which is useful for moving the feed to a convenient hour.
Enter Autolyse in minutes, or 0 to skip that rest.
Under Proof the shaped loaf, choose In the fridge or At room temperature. For the fridge, set Hours in the fridge.

The summary shows Bulk fermentation (guide), Final proof and Feed to bake, followed by the full timeline. Steps that land between 11 PM and 6 AM are marked Night.

Worked example: a Saturday morning loaf

You want to bake at 9:00 AM on Saturday. The kitchen is 21 °C, the dough uses 20% starter, autolyse is 45 minutes, and the shaped loaf will spend 14 hours in the fridge. With a 1:2:2 feed, the planner puts the feed at 2:00 AM on Friday and flags it as a night step.

Switch Starter feed ratio to 1:5:5. The slower feed now peaks in about 10 h to 15 h, and the plan becomes:

Thursday 10:35 PM: feed the starter
Friday 10:15 AM: mix flour and water for the autolyse
Friday 11:00 AM: add starter and salt
Friday 11:30 AM: first of four sets of stretch and folds, the last at 1:00 PM
Friday 6:30 PM: bulk ends, pre-shape (guide)
Friday 7:00 PM: shape and put the loaf in the fridge
Saturday 8:00 AM: preheat the oven
Saturday 9:00 AM: bake
Saturday 9:45 AM: out of the oven

The summary reads Bulk fermentation (guide): about 6 h 15 min to 8 h 30 min, Final proof: 14 h, and Feed to bake: 35 h 15 min. The plan uses the middle of the bulk range, so start checking the dough at about 5:15 PM, when the short end of that range is reached, rather than waiting for the clock.

For contrast, a same-day loaf at 24 °C with a 1:1:1 feed and a room-temperature proof, baked at 5:00 PM, needs the starter fed at 4:15 AM. That early start is why so many home bakers lean on the fridge.

Getting the most from the plan

The fridge is your buffer. A cold proof can run anywhere from about 8 to 16 hours for many doughs, which absorbs the uncertainty in bulk fermentation.
Control the dough temperature. A dough that starts warmer or cooler than the room throws every estimate off, so let the dough water temperature calculator pick your mixing water.
Keep notes. A couple of bakes will show whether your starter runs ahead of the estimates or behind them.
Size the feed properly. The starter feeding calculator turns the chosen ratio into exact weights.

Schedule questions

Why does the plan change so much with a few degrees?

A 3 °C difference can shift bulk fermentation by an hour or more, and the effect adds up across the feed, bulk and proof.

Can I shorten bulk fermentation if I’m running late?

Moving the dough somewhere warmer speeds it up. Cutting bulk short without that usually gives a dense loaf, so it is better to shift the bake time.

What if the dough is ready long before the plan says?

Go with the dough. Shape it and move on to the proof. A fridge proof gives you plenty of room to get back on schedule.

Why use a percentage of flour for starter?

It keeps the number meaningful at any batch size, and it is the figure that controls speed. The sourdough recipe builder uses the same basis, so you can carry the value straight across.