How long to proof sourdough at 73°F (23°C)
The sweet spot most sourdough recipes are written for.
At 73°F (23°C)
Estimate- Bulk fermentation
- 4½–6½ h
- Final proof
- 1¾–2¾ h
- Starter peak
- 3¾–5¾ h
20% levain, to a 50–75% rise
at room temperature, or 12–16 h in the fridge
after a 1:1:1 feed (4½–6¾ h at 1:2:2)
Compared with 75°F (24°C), everything here takes about 9% longer. Each 1°F changes the times by about 4%. Want today's numbers for your kitchen? Try the live rise forecast.
Proofing times at 73°F (23°C)
| Stage | Estimated time |
|---|---|
| Starter peak, 1:1:1 feed | 3¾–5¾ h |
| Starter peak, 1:2:2 feed | 4½–6¾ h |
| Starter peak, 1:5:5 feed | 6¾–10¼ h |
| Bulk fermentation, 10% levain | 6–9 h |
| Bulk fermentation, 15% levain | 5–7½ h |
| Bulk fermentation, 20% levain | 4½–6½ h |
| Bulk fermentation, 30% levain | 3½–5¼ h |
| Final proof, room temperature | 1¾–2¾ h |
| Cold retard (fridge, 3–5°C / 37–41°F) | 8–48 h, best 12–16 h |
Ranges are the estimate ±20%, rounded to the quarter hour. Dough at about 75% hydration.
What to expect at 73°F
73°F (23°C) sits in the range most sourdough recipes are written for, and many bakers aim for a dough temperature of 75–78°F (24–26°C) on purpose. Bulk with 20% levain takes about 4½–6½ hours, long enough to build flavour and strength and short enough to fit in a day.
This is where the classic target applies: end bulk at a 50–75% rise, when the dough is domed, jiggly and bubbly at the edges, then shape.
How to keep the dough in the sweet spot
- Check the dough itself with a probe thermometer after mixing, not just the room.
- Adjust the water temperature to land the dough at 75–78°F (24–26°C); this is what bakers call the desired dough temperature.
- Use a straight-sided container and mark the starting level, so a 50–75% rise is easy to see.
- Do your stretch and folds in the first half of bulk, then leave the dough alone.
Main risk: trusting the timer over the dough
Both under- and over-proofing are possible at 73°F, but the range is forgiving. Start checking at about 4½ hours and judge by the rise and the jiggle, not the clock.
Your starter at 73°F
At 73°F (23°C) a 1:1:1 feed peaks in about 3¾–5¾ hours, 1:2:2 in about 4½–6¾ hours and 1:5:5 in about 6¾–10¼ hours.
Twice-daily feeds at 1:2:2, or a single overnight 1:5:5 feed, keep a starter on a comfortable rhythm at this temperature.
Cold retard or room-temperature proof?
At 73°F you can choose: proof the shaped loaf on the counter for about 1¾–2¾ hours, or refrigerate it for 8–48 hours (best 12–16 h) at 3–5°C (37–41°F). The fridge adds flavour and lets you bake whenever suits you.
A sample plan at 73°F
To bake at 9:00 am after a 14-hour cold retard, with a 1:2:2 feed and 20% levain, the centre estimates line up like this:
- 7:05 AM Day 1 Feed your starter 1:2:2 peaks in about 4½–6¾ h
- 12:45 PM Day 1 Mix the dough (starter at its peak) bulk: about 4½–6½ h
- 6:15 PM Day 1 Bulk done? Pre-shape and shape about 45 min with a bench rest
- 7:00 PM Day 1 Shaped loaf into the fridge cold retard, 14 h
- 9:00 AM Day 2 Bake straight from the fridge preheat your oven about 45 min earlier
Skipping the fridge? Proof the shaped loaf on the counter for about 1¾–2¾ hours and bake around 9:10 PM on day 1. Build your own timeline with the sourdough schedule calculator.
A degree or two either side
Kitchen thermometers and thermostats rarely agree to the degree. Here's how the times shift around 73°F; the full 60–90°F table is on the bulk fermentation chart.
Watch the dough, not the clock
Starter at its peak
- Roughly doubled (or more) since the feed
- Domed top, just before it flattens
- Bubbly all the way through, pleasantly tangy
Bulk fermentation done
- Risen about 50–75% in volume
- Jiggly when you shake the container, domed edges
- Bubbles on the sides and top, airy and light
Final proof: the poke test
- Springs back fast: needs more time
- Springs back slowly, small dent stays: bake
- Dent stays and the dough sighs: over-proofed, bake now
How these estimates work
Temperature is the main driver. Sourdough is a living culture, and as a rule of thumb it works about 2× faster for every 9°C (16°F) warmer, and half as fast for every 9°C cooler. That's why the same recipe can take 4 hours in July and 9 in January.
Starter peak: a healthy starter fed 1:1:1 peaks in about 5 hours at 72°F (22°C), 1:2:2 in about 6
and 1:5:5 in about 9. In numbers: (4 + n) × 2^((22 − °C) ÷ 9) hours for a 1:n:n feed, kept between 3 and
14 hours on the counter. In the fridge, expect 1–5 days.
Bulk fermentation: a dough with 20% levain at about 75% hydration takes about 5 hours at 75°F
(24°C) to rise 50–75%: 5 × 2^((24 − °C) ÷ 9) hours. Less levain is slower (10% ≈ ×1.35, 15% ≈ ×1.15),
more is faster (30% ≈ ×0.8). The final proof at room temperature takes about 0.4 × the bulk time;
a cold retard in the fridge (3–5°C / 37–41°F) works anywhere from 8 to 48 hours, best 12–16.
Every number is shown as a range (±20%), never an exact time, because starter strength, flour and hydration vary from kitchen to kitchen. It's the same model the Boulie app starts from, and the app then learns your starter's actual rhythm from your feeds and rise checks.
Frequently asked questions
How long does sourdough take to proof at 73°F (23°C)?
At 73°F, expect bulk fermentation of about 4½–6½ hours with 20% levain, then a final proof of about 1¾–2¾ hours at room temperature, or 8–48 hours (best 12–16 h) at 3–5°C (37–41°F) in the fridge. These are estimates: end bulk at about a 50–75% rise and use the poke test for the final proof.
How long does a sourdough starter take to peak at 73°F?
About 3¾–5¾ hours after a 1:1:1 feed, 4½–6¾ hours at 1:2:2 and 6¾–10¼ hours at 1:5:5. Use it when it has roughly doubled and the top is domed, before it starts to fall.
Is 73°F a good temperature for proofing sourdough?
Yes. 73°F (23°C) is in the 72–78°F range most recipes are written for. Bulk with 20% levain takes about 4½–6½ hours to a 50–75% rise, and a final proof takes about 1¾–2¾ hours at room temperature.