Sourdough Starter Feeding Ratio Calculator

What a feeding ratio really means

A sourdough starter feeding ratio is expressed as Starter : Flour : Water by weight. The numbers describe parts:

• 1:1:1 = equal weights of all three (e.g., 50g starter + 50g flour + 50g water)
• 1:2:2 = double the flour and water (50g starter + 100g flour + 100g water)
• 1:5:5 = five times the flour and water (50g starter + 250g flour + 250g water)
• 1:10:10 = ten times (50g starter + 500g flour + 500g water)

The ratio of starter-to-food (flour + water) determines how quickly the wild yeast and bacteria can ferment the new flour. Lower starter ratio = more food per yeast cell = slower fermentation but bigger ultimate rise.

The ecosystem inside your jar

A mature sourdough starter is a complex microbial community, not just yeast. The major players:

Wild yeasts:

• Saccharomyces cerevisiae (sometimes; same as bread yeast)
• Candida humilis (the most common in sourdough)
• Kazachstania species
• Other naturally occurring yeasts from flour and environment

Lactic acid bacteria (LAB):

• Lactobacillus sanfranciscensis (famous for SF sourdough)
• Lactobacillus brevis
• Lactobacillus plantarum
• Many other species

The ratio of yeast to LAB determines flavor and rise:

• More yeast = more leavening power, milder flavor
• More LAB = more sourness, less rise

A 1:1:1 starter at room temperature favors LAB growth (more sour). A 1:5:5 starter has more food per cell, favoring yeast growth (milder, better rise).

How feeding ratio affects timing

Approximate peak times at 75°F (24°C):

“Food” here means flour plus water together. A 1:5:5 feed gives each part of starter ten parts of food, which is what the calculator uses to pick a peak window.

At 65°F (18°C) those times run about 70% longer, and at 85°F (29°C) they roughly halve. Both figures come off the temperature table further down, and the calculator prints all three so you do not have to interpolate.

These are rough guides. Real timing depends on starter strength, flour type, ambient temperature, and how long it’s been since the last feeding.

Choosing a feeding schedule

1:1:1 daily: traditional approach

• Pros: starter ready quickly, manageable amounts
• Cons: requires daily attention, more sour flavor
• Best for: bakers who bake several times per week

1:2:2 daily: balanced

• Pros: good rise, moderate sourness, somewhat forgiving
• Cons: still daily commitment
• Best for: weekly bakers

1:5:5 every 12 hours: peak fermentation control

• Pros: strong starter, great rise, complex flavor
• Cons: more food, jar grows quickly
• Best for: serious bakers wanting maximum performance

1:10:10 daily or every 24 hours: low-maintenance

• Pros: feed once daily, milder flavor, predictable
• Cons: needs to be timed with bake schedule
• Best for: occasional bakers

Refrigerator storage (any ratio + 1-2 weeks rest):

• Pros: feed once per week
• Cons: requires “wake-up” feedings before bake
• Best for: bakers who bake 1-2 times per month

Starter hydration

Hydration = water weight ÷ flour weight × 100%

Stiff starters (50-70% hydration):

• Less surface area = slower acid development = milder, less sour
• Concentrate yeast activity
• Used for panettone, brioche, sweet breads
• Italian tradition (lievito madre, pasta madre)

Standard starters (100% hydration):

• Most common for everyday sourdough
• Easy to maintain and measure

Wet starters (125%+ hydration):

• More acidic
• More open crumb in finished bread
• Some commercial bakeries use these
• Can be unstable in hot weather

Levain vs starter, an important distinction

Starter (mother culture): the small jar of culture you maintain perpetually. Usually 50-100g. Fed regularly, used to seed levains for specific bakes.

Levain (sometimes called “preferment” or “offshoot”): a portion of starter fed specifically for one bake. Built to the exact size and hydration needed for the recipe.

Example workflow for a single sourdough boule:

1. Take 10g of mother starter from the refrigerator
2. Build a levain: 10g starter + 50g flour + 50g water (a 1:5:5 build)
3. Wait 6-12 hours for the levain to peak
4. Use the full 110g levain in your bread recipe
5. Feed the mother starter (1:1:1) and return to fridge

This way you don’t waste starter, your mother stays small, and you build optimal levain for each specific bake.

Reading starter activity

Healthy starter at peak shows:

• Domed top, slightly cracked
• At least doubled in volume, and often tripled on a 1:5:5 or higher feed (mark the start level with a rubber band)
• Bubbles throughout when viewed through the glass
• Tangy aroma, pleasantly sour and slightly fruity (banana, vinegar, mild yogurt)
• Float test passes: a spoonful floats in room-temperature water

A 1:1:1 feed rarely triples. There is not enough fresh flour in the jar to support that much gas, so doubling is the honest target at low ratios and tripling is what the big feeds buy you.

Warning signs:

• Liquid layer on top (hooch): starter is hungry but not dangerous; just stir it back in
• Gray or pink discoloration: contamination; discard
• Mold spots: contamination; discard
• Strong nail-polish or acetone smell: very over-fermented; needs aggressive feeding
• No rise at all: dormant or starved; feed more frequently

Reviving a refrigerated starter

To wake up a refrigerated starter:

1. Take from fridge, let warm to room temp (1-2 hours)
2. Feed 1:1:1 or 1:2:2; let peak (6-8 hours typical)
3. Discard most; feed again 1:5:5; let peak
4. Optionally do one more feeding 1:5:5 the day of baking

This 2-3 feeding revival ensures peak activity. A starter pulled directly from the fridge produces less leavening power.

Common ratios for specific applications

Note the panettone row: the water part is what makes a starter stiff, not the flour part. A 1:0.5:0.5 feed is still 100% hydration, just a very small one.

Discard, the byproduct everyone hates

When you feed a 1:5:5 starter, you typically discard everything except a portion to keep the math manageable. This “discard” can be:

• Composted
• Used in pancakes, waffles, crackers
• Added to bread recipes for flavor
• Refrigerated and used within a week

A common workflow: keep mother starter small (20-30g). Build levain for baking. Daily feeding produces minimal discard.

Temperature sensitivity

Sourdough fermentation rate roughly doubles for every 15°F (8°C) increase. Practical implication:

Hot kitchens require shorter timings or lower feeding ratios. Cold kitchens need longer timings or higher temperatures (proofing box, oven with light on).

In a July kitchen at 85°F, a 1:1:1 feed can peak and collapse in under three hours. That is the single most common reason a starter that worked fine all winter suddenly smells of acetone in summer. Feed it 1:5:5 or move the jar somewhere cooler and the problem usually disappears within two days.