How long to proof sourdough at 63°F (17°C)
Slow, sour and forgiving: plan for a long bulk or warm the dough up.
At 63°F (17°C)
Estimate- Bulk fermentation
- 6¾–10 h
- Final proof
- 2¾–4 h
- Starter peak
- 5¾–8¾ h
20% levain, to a 75–100% rise
at room temperature, or 12–16 h in the fridge
after a 1:1:1 feed (7–10½ h at 1:2:2)
Compared with 75°F (24°C), everything here takes about 67% 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 63°F (17°C)
| Stage | Estimated time |
|---|---|
| Starter peak, 1:1:1 feed | 5¾–8¾ h |
| Starter peak, 1:2:2 feed | 7–10½ h |
| Starter peak, 1:5:5 feed | 10½–15½ h |
| Bulk fermentation, 10% levain | 9–13¾ h |
| Bulk fermentation, 15% levain | 7¾–11¾ h |
| Bulk fermentation, 20% levain | 6¾–10 h |
| Bulk fermentation, 30% levain | 5½–8 h |
| Final proof, room temperature | 2¾–4 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 63°F
At 63°F (17°C) sourdough runs slow. Bulk fermentation with 20% levain takes about 6¾–10 hours, and for the first few hours the dough barely seems to move. That's normal: the culture is working, just at a fraction of the pace most recipes assume.
Slow fermentation has an upside. Acidity has more time to build relative to the rise, so loaves proofed cold tend to taste tangier. The catch is judging when bulk is done: cool dough looks sleepy even when it's close, so let it go further than you would in summer, towards a 75–100% rise, and look for bubbles on the sides of the container.
How to warm up a cold dough
- Mix with warm water, around 90–95°F (32–35°C), so the dough starts near 75–78°F (24–26°C) instead of the room temperature.
- Use the oven with only the light on, door closed. Check it with a thermometer first: some ovens climb past 85°F (29°C).
- Put the dough in the microwave or a cooler box next to a mug of just-boiled water, and swap the water every hour or so.
- Use more levain (25–30% instead of 20%) to shorten bulk by roughly a fifth.
Main risk: under-fermentation
Ending bulk by the clock at 63°F usually means under-fermented dough: tight, hard to shape, and a dense, gummy crumb with a few big holes under the crust. If the dough hasn't grown and isn't bubbly at the sides, give it more time, even if that's 10 hours or longer.
Your starter at 63°F
A starter at 63°F (17°C) takes its time: about 5¾–8¾ hours to peak after a 1:1:1 feed, 7–10½ hours at 1:2:2 and 10½–15½ hours at 1:5:5.
To speed it up, feed at 1:1:1 with lukewarm water, add 10–20% whole wheat or rye flour to the feed, and keep the jar in the warmest spot you have. A starter that looks dead in a cold kitchen is usually just slow.
Cold retard or room-temperature proof?
At 63°F a fridge retard is optional rather than essential: your kitchen is already slowing things down. It's still handy for timing. After a long cool bulk, shape, then refrigerate for 8–48 hours (best 12–16 h) at 3–5°C (37–41°F), or proof on the counter for about 2¾–4 hours.
A sample plan at 63°F
To bake at 9:00 am after a 14-hour cold retard, with a 1:5:5 feed and 20% levain, the centre estimates line up like this:
- 8:50 PM Evening before Feed your starter 1:5:5 peaks in about 10½–15½ h
- 9:50 AM Day 1 Mix the dough (starter at its peak) bulk: about 6¾–10 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 2¾–4 hours and bake around 10:20 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 63°F; the full 60–90°F table is on the bulk fermentation chart.
| Temp | Starter peak 1:1:1 | Starter peak 1:2:2 | Bulk ferment 20% levain | Final proof room temp |
|---|---|---|---|---|
| 61°F / 16°C | 6¼–9½ h | 7½–11¼ h | 7¼–11 h | 3–4½ h |
| 62°F / 17°C | 6–9 h | 7¼–10¾ h | 7–10½ h | 2¾–4¼ h |
| 63°F / 17°C | 5¾–8¾ h | 7–10½ h | 6¾–10 h | 2¾–4 h |
| 64°F / 18°C | 5½–8¼ h | 6¾–10 h | 6½–9¾ h | 2½–4 h |
| 65°F / 18°C | 5¼–8 h | 6¼–9½ h | 6¼–9¼ h | 2½–3¾ h |
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 75–100% 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 63°F (17°C)?
At 63°F, expect bulk fermentation of about 6¾–10 hours with 20% levain, then a final proof of about 2¾–4 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 75–100% rise and use the poke test for the final proof.
How long does a sourdough starter take to peak at 63°F?
About 5¾–8¾ hours after a 1:1:1 feed, 7–10½ hours at 1:2:2 and 10½–15½ hours at 1:5:5. Use it when it has roughly doubled and the top is domed, before it starts to fall.
How can I make sourdough rise faster at 63°F?
Warm the dough rather than waiting on the room. Mix with water at about 90–95°F (32–35°C), proof in an oven with just the light on or next to a mug of hot water, and use 25–30% levain. At 63°F with 20% levain, bulk takes about 6¾–10 hours; at 75°F it would take about 4–6.