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Sourdough starter peak time calculator

At 70 °F, a 1:1:1 feeding peaks in 4 to 6.5 hours and a 1:5:5 feeding in 10 to 15 hours. Warm the kitchen and the times get shorter. Set your own temperature in the tool below.

What do you know?

The starter left in the jar after you discard.

Weigh the jar, then subtract the empty jar. We use it to tell you how much to discard.

Feeding ratio (starter : flour : water)

1:5:5 means 1 part starter, 5 parts flour and 5 parts water, by weight.

Slower and milder. Suits one feeding a day. 1:1:1 versus 1:5:5

Your feeding

Show amounts in grams, ounces or cups

Feed 50 g starter, 250 g flour and 250 g water.

Starter
50 g
Flour
250 g
Water
250 g
Total after feeding
550 g

Discard

Type the weight of the starter in your jar to see how much to discard.

Keep 50 g of starter in the jar and discard the rest. Then add the flour and water. Ratio 1:5:5 by weight, 100% hydration.

Rough peak time

about 10 to 15 hours

At 70 °F. A guide only: your flour, starter and kitchen will change it. Watch the jar, not the clock.

Fine-tune

100% means equal flour and water. Used with the preset ratios.

Temperature unit

Used only for the peak time guide.

Clock times (optional)

Fill in one to see clock times for the peak. Fill in both to get a ratio that fits your night.

Flour mix (optional)

White flour (all-purpose or bread): 100%

The numbers

Rough peak time by feeding ratio and kitchen temperature
Ratio65 °F70 °F75 °F80 °F85 °F
1:1:15 to 7.5 hours4 to 6.5 hours3.5 to 5 hours3 to 4.5 hours2.5 to 3.5 hours
1:2:28 to 12 hours6 to 10 hours5.5 to 8 hours4.5 to 6.5 hours3.5 to 5.5 hours
1:3:39 to 14 hours8 to 12 hours6 to 10 hours5.5 to 8 hours4.5 to 6.5 hours
1:5:512 to 18 hours10 to 15 hours8 to 12 hours7 to 10 hours5 to 8 hours
1:10:1015 to 23 hours13 to 19 hours10 to 16 hours9 to 13 hours7 to 11 hours

Amounts use 100% hydration and white flour. Change hydration or the flour mix in the tool above.

What affects the peak time

Two things matter most: how much you dilute the starter and how warm the jar is. A larger ratio spreads the yeast thin, so it needs longer to grow back. Every 18 °F (10 °C) of extra warmth cuts the wait about in half.

Flour matters too. Whole wheat and rye feed the yeast more, so the peak often comes sooner. A starter that is young, weak or recently out of the fridge is slower than a healthy one.

How to spot the peak

Mark the starting level with a rubber band. At the peak the starter has about doubled, the top is domed, and the surface is full of bubbles. A starter that has started to fall has a flat or dipped top and a stronger smell.

Use the starter at or just after the peak. Feed again if you will not bake soon.

When the table does not apply

Below 59 °F or above 95 °F the tool shows no time, because a starter behaves in unpredictable ways there. Find a warmer or cooler spot. The oven with only the light on is a common warm place.

Quick answers

How long does it take a starter to peak at room temperature?

At 75 °F, from 3.5 to 5 hours for a 1:1:1 feeding to 10 to 16 hours for a 1:10:10 feeding.

Is this peak time exact?

No. It is a rough guide for an active starter at 100% hydration. Watch the jar and learn how your own starter behaves.

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