What does a sourdough starter feeding ratio like 1:2:2 mean?

A feeding ratio of 1:2:2 means 1 part existing starter, 2 parts flour, and 2 parts water by weight. For example, if you keep 20g of starter, you'd add 40g flour and 40g water for a total of 100g. The ratio controls fermentation speed — higher ratios (more flour and water relative to starter) mean slower, more flavorful fermentation.

What is the best feeding ratio for sourdough starter?

It depends on your schedule. Use 1:1:1 for a quick 4–6 hour turnaround, 1:2:2 for standard daily maintenance (6–8 hours), or 1:5:5 for overnight feeds (10–12 hours). If your kitchen is warm (above 78°F/26°C), use a higher ratio to prevent over-fermentation. If it's cool (below 68°F/20°C), use a lower ratio.

How much starter do I need to keep when feeding?

You only need to keep a small amount — typically 10–25g is enough. The rest becomes discard that you can use in pancakes, waffles, crackers, or pizza dough. Keeping less starter and feeding with a higher ratio (like 1:5:5) produces a more vigorous, sweet-smelling starter with better rise.

How do I know when my sourdough starter is at peak?

A starter at peak has roughly doubled in volume, looks domed on top (not flat or sunken), has visible bubbles throughout, and smells pleasantly yeasty — like ripe fruit or mild vinegar. If it has collapsed or smells strongly of acetone or alcohol, it's past peak and has been over-fermented. The float test (dropping a spoonful in water) can also help — a peak starter floats.

What is inoculation percentage in sourdough baking?

Inoculation percentage is the amount of starter (seed) as a percentage of the total flour. It's calculated as (starter weight ÷ flour weight) × 100. Higher inoculation (50–100%) means faster fermentation. Lower inoculation (5–10%) means slower, more flavor-developing fermentation — common in artisan bakeries that do long overnight builds.

Does flour type affect sourdough starter fermentation time?

Yes, significantly. Whole wheat and rye flours ferment 20–30% faster than all-purpose or bread flour because they contain more natural sugars, minerals, and wild yeast. Rye is especially active. Many bakers use a mix — like 50% AP and 50% whole wheat — for a balance of activity and flavor.

How does temperature affect sourdough starter timing?

Temperature is the biggest variable. At 72°F (22°C), a 1:2:2 feed peaks in about 6–8 hours. At 80°F (27°C), the same feed might peak in 5–7 hours. At 65°F (18°C), it could take 7–10 hours. For precise scheduling, keep your starter in a consistent-temperature spot. An oven with just the light on typically stays around 78–80°F.

Can I use this calculator for building a levain?

Absolutely. A levain is simply a portion of starter built up to a specific amount for a recipe. Enter the total levain weight your recipe calls for, choose your preferred ratio (many bakers use 1:2:2 or 1:5:5 for levains), and the calculator gives you the exact amounts of mature starter, flour, and water to mix.

How do I calculate the amount of sourdough starter for multiple loaves?

Most sourdough recipes call for 50–200g of active starter per loaf. Multiply the per-loaf amount by the number of loaves, then add 25–50g buffer (to keep your starter culture going). Enter that total into the calculator. For example: 100g per loaf × 3 loaves + 50g buffer = 350g total starter needed.

Sourdough Starter Calculator

Total Starter Needed (g)

How much active starter you need for your recipe

Feeding Ratio (Starter : Flour : Water)

Flour Type

Standard fermentation speed baseline

Ambient Temperature

Warmer = faster fermentation. Ideal range: 70–80°F

Feeding Breakdown — 1:2:2

Starter

40.0

grams

Flour

80.0

grams

Water

80.0

grams

Starter 20%Flour 40%Water 40%

Starter Metrics

Key properties of your starter feed

Feed Hydration

100.0%

Added Water ÷ Added Flour

Inoculation

50.0%

Starter ÷ Flour

Est. Peak

5.9–7.9 hours

at 72°F

Feeding Ratio Reference

Estimated times at ~72°F (22°C) with AP flour

Ratio	Time to Peak	Best For
1:1:1	4–6 hours	Quick feed, mild flavor
1:2:2	6–8 hours	Standard daily maintenance
1:3:3	8–10 hours	Balanced flavor development
1:5:5	10–12 hours	More complex flavor
1:10:10	16–24 hours	Overnight / cold retard

What Is a Sourdough Starter Calculator?

Calculate exact feeding amounts for your sourdough starter

S:F:W

Ratio

Starter : Flour : Water

100%

Feed Hydration

Added water ÷ added flour

4–24h

Peak Time

Based on ratio & temp

A Sourdough Starter Calculator determines the exact amounts of starter (seed), flour, and water you need based on your chosen feeding ratio and the total amount of active starter your recipe requires.

Whether you search for a sourdough starter ratio calculator, sourdough starter feeding calculator, or levain calculator, this tool calculates precise gram amounts, feed hydration percentage, inoculation rate, and estimated time to peak activity — adjusted for your temperature and flour type.

Timing is an estimate

Peak times depend on your starter's maturity, flour brand, water quality, and exact temperature. Use the calculated times as a starting point and adjust based on observation — your starter is ready when it has doubled and looks domed, not when the clock says so.

How Feeding Amounts Are Calculated

Step-by-step formula with ratio-based proportions

Component Weights

Starter = Total × S ÷ (S + F + W)
Flour = Total × F ÷ (S + F + W)
Water = Total × W ÷ (S + F + W)

Proportional split by ratio parts

Feed Hydration & Inoculation

Feed Hydration % = Added Water ÷ Added Flour × 100
Inoculation % = Starter ÷ Added Flour × 100

Measures the feed ingredients only, not total starter hydration

Worked Example: 200g at 1:2:2

Total Parts

1+2+2

Starter

grams

Flour

grams

Water

grams

Feed Hydration

100

percent

Inoculation

percent

Feeding Ratio Quick Reference

How ratio affects timing and flavor at ~72°F (22°C) with AP flour

Ratio	Peak Time	Inoculation	Best For
1:1:1	4–6 hrs	100%	Quick build, mild flavor
1:2:2	6–8 hrs	50%	Daily maintenance (most common)
1:3:3	8–10 hrs	33%	Balanced flavor development
1:5:5	10–12 hrs	20%	Complex flavor, overnight
1:10:10	16–24 hrs	10%	Cold retard, max flavor depth

Lower inoculation = more flavor: A 1:5:5 ratio gives the yeast and bacteria more flour to consume over a longer period, producing more organic acids (flavor) before peaking. Higher ratios like 1:1:1 are faster but produce a milder-tasting starter.

How Temperature Affects Fermentation

Why timing varies with ambient conditions

Warmer (75–85°F / 24–29°C)

Faster fermentation, more lactic acid, tangier flavor. Use higher ratios (1:3:3+) to prevent over-fermentation. Great for quick builds.

Cooler (60–70°F / 16–21°C)

Slower fermentation, more acetic acid, complex flavor. Use lower ratios (1:1:1 to 1:2:2). Ideal for overnight or cold-retard builds.

Flour Type	Speed	Why
All-Purpose / Bread	Baseline	Standard mineral and enzyme content
Whole Wheat	~20% faster	Higher bran minerals and wild yeast
Rye	~30% faster	Highest enzyme activity of any grain

Tips for Consistent Results

Practical advice for reliable sourdough feeding

Weigh, Don't Measure by Volume

Flour density varies by type and how it's scooped. A kitchen scale gives accurate, repeatable results. Even a $10 scale makes a huge difference.

Always Add a Buffer

Make 25–50g more starter than your recipe needs. You need to keep some back to maintain your culture — never use all of it.

Use Filtered or Dechlorinated Water

Chlorine can slow or kill the microorganisms in your starter. Let tap water sit uncovered for 24 hours, or use filtered water.

Watch the Starter, Not the Clock

Peak times are estimates. Your starter is ready when it has doubled in volume and looks domed on top — not flat or collapsed.

Frequently Asked Questions

Common questions about sourdough feeding ratios, hydration, and timing

Feed hydration is the ratio of added water to added flour in a single feeding, calculated as (added water ÷ added flour) × 100. A standard 1:1:1 or 1:2:2 ratio with equal flour and water gives 100% feed hydration — a thick, pancake-batter consistency. Lower feed hydration (50–65%) creates a stiffer starter (pasta madre style), while higher feed hydration (125%+) creates a more liquid, pourable starter. Note: this measures only the ingredients you add, not the total hydration of the resulting starter, which also depends on the seed starter's hydration.

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Last updated Apr 23, 2026

Sourdough Starter Calculator

Starter Metrics

Feeding Ratio Reference

What Is a Sourdough Starter Calculator?

How Feeding Amounts Are Calculated

Feeding Ratio Quick Reference

How Temperature Affects Fermentation

Tips for Consistent Results

Frequently Asked Questions

Embed Sourdough Starter Calculator

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