How often should I feed my sourdough starter?

If kept at room temperature, feed once or twice daily. If stored in the fridge, once a week is enough to keep it alive, though feeding before every bake produces a stronger result.

Can I feed my starter with self-raising flour?

No. The added raising agents in self-raising flour will interfere with the culture. Use plain bread flour or all-purpose flour.

What if I forget to feed my starter for a week?

If it was on the counter, it may smell very sour or have hooch on top. Pour off the hooch, discard down to 20g, and feed with fresh flour and water. Give it 2–3 regular feeds over 48 hours before trying to bake.

Does the water-to-flour ratio have to be equal?

Not at all. Equal parts flour and water gives 100% hydration. You can run your starter stiffer (less water) or looser (more water) depending on preference. Most beginners start with 100% hydration because it's easy to calculate and observe.

Can I use my starter straight from the fridge?

You can, but it will be sluggish and underripe. Always bring it to room temperature and let it peak after at least one feed before using for bread. For discard recipes, straight-from-fridge is fine.

How do I know how much discard I have?

Everything you removed before feeding is discard. Use the sourdough discard calculator to see the exact flour and water breakdown at any hydration level.

How to Feed Your Sourdough Starter — Ferment Calculator

Feeding a sourdough starter means adding fresh flour and water to the existing culture so the wild yeast and bacteria have food to consume. Done consistently, feeding keeps your starter strong, active, and ready to leaven bread. Done poorly — wrong ratios, wrong timing, wrong temperature — it leaves you with a sluggish or unbalanced culture.

What happens when you feed

When you add flour and water, the wild yeast and lactic acid bacteria begin consuming the sugars in the flour. Yeast produces carbon dioxide (which makes bread rise) and ethanol. Bacteria produce lactic and acetic acids, which give sourdough its flavour and help preserve the finished loaf.

After each feed the culture moves through four phases. Your job is to use the starter at or just before peak, then feed it again before it collapses too far and the acid load builds up.

1
Lag phase The first 1–2 hours after feeding. Minimal visible activity while the culture wakes up and starts metabolising the fresh flour.
2
Rise phase The culture accelerates, producing CO₂ and expanding in volume. Bubbles appear throughout and the surface begins to dome.
3
Peak Maximum volume, roughly doubled, domed and airy. This is the ideal moment to use the starter for baking.
4
Fall The food is depleted, the starter deflates, and acids accumulate. Feed again around here — not after it has fully collapsed.

Feeding ratios explained

A feeding ratio describes the proportion of old starter to flour to water, always by weight, in the format starter : flour : water. The higher the ratio (more food per unit of starter), the longer it takes to peak and the milder the flavour. A lower ratio peaks faster but produces a more acidic culture.

1:1:1 — equal parts Feed 20g starter with 20g flour and 20g water. Peaks quickly (4–6h at 24°C). Ideal for same-day baking and reviving a sluggish starter.

1:2:2 — double the food Peaks in 6–9h at 24°C. A good overnight ratio: feed in the evening, use it the next morning.

1:5:5 — slow build Peaks in 10–14h at 24°C. Dilutes the acid load for a milder starter, and paces a long overnight or warm-kitchen build.

You are not limited to round numbers. A 1:3:4 feed produces a stiffer starter at about 80% hydration; a 1:2:3 gives 150%. The sourdough feeding calculator gives exact grams for any ratio and hydration.

How much starter to keep

Most home bakers keep far more starter than they need. You only need a small seed to feed from — typically 10–30g. Everything else is discard.

A practical approach: decide how much starter your recipe needs (usually 100–200g), then back-calculate from your chosen ratio. For a 1:5:5 feed producing 200g total, keep 18g starter and add 91g flour and 91g water. Keeping the maintained amount small wastes less flour and keeps the acid load low — carrying over too much old starter starves the culture faster.

Discard: what it is and what to do with it

Every time you feed, you remove most of the old starter before adding fresh flour and water. That removed portion is discard. It is not waste — it is unfed starter with a mildly sour flavour that works well in many recipes: pancakes and waffles, crackers, pizza dough, banana bread and muffins, and flatbreads.

Discard keeps in a separate container in the fridge for up to a week.

Try the calculator

Sourdough Discard Calculator

See exactly how much flour and water is in your discard at any hydration level.

Open calculator →

Counter vs fridge: which schedule fits you

There is no single right schedule — it depends on how often you bake. Match the routine to your habits rather than forcing daily feeds you will not keep up with.

Counter (room temperature) Feed once or twice daily. The starter stays in continuous active fermentation, always ready within a few hours of peaking. Best if you bake 3–5 times a week — but it uses more flour and demands consistency.

Fridge (weekly maintenance) Feed, let it sit 1–2 hours to get going, then refrigerate. Feed once a week to keep it alive. Pull it out 12–24 hours ahead, feed once or twice at room temp, and use it at peak. Best for baking weekly or less.

The hybrid Keep it in the fridge most of the time, pull it out 1–2 days before a planned bake, feed twice daily to build strength, bake, then return it to the cold.

Which flour to feed with

Different flours feed the culture at different speeds. You can lean on the faster ones to wake a sluggish starter, or stick with a steady base for predictability.

White bread flour the standard — consistent, predictable, mild. Higher protein feeds the culture well.

Rye flour the strongest accelerant; even 5–10% dramatically speeds fermentation and adds complex flavour.

Wholemeal / whole wheat ferments faster thanks to extra wild yeast and nutrients; add 10–20% to revive or speed up.

All-purpose flour works, but its lower protein makes a slower, less active culture than bread flour.

Bleached flour avoid — the bleaching agents can inhibit yeast activity.

Water for feeding

Use room-temperature water. If your tap water is heavily chlorinated, leave it in an open container for 30 minutes before using, or use filtered water — chlorine can inhibit bacterial activity.

Water temperature matters most in cold kitchens. Slightly warm water (26–28°C) helps get the culture active faster in winter, while cold water slows it from the moment of feeding.

Signs your feeding routine is working

When your ratio, flour, and timing are locked in, the starter behaves predictably. Look for all of these together.

Reliable double rises to roughly twice its volume within your expected window after each feed.

Consistent peak timing peaks at about the same time each cycle at the same temperature.

Clean smell yeasty and mildly tangy, with no harsh vinegar or acetone notes.

Domed, bubbly surface bulges upward at peak with bubbles visible throughout — not flat.

If your starter is inconsistent — sometimes doubling in 4 hours, sometimes 12 — the usual culprits are temperature swings, inconsistent flour, or varying how much old starter you carry over. Lock in all three and results steady out.

Common feeding mistakes

! Watch for

Feeding too much at once — 1:10:10 overwhelms a sluggish starter; build up from 1:1:1.
Feeding at the wrong time — wait until it is past peak and starting to fall, not fully collapsed and starving.
Using cold water in winter — it slows the culture immediately; use room-temperature water year-round.
Not discarding enough — too much carried-over starter lets the old acid load dominate the fresh feed.
Switching flour brands mid-routine — different protein and yeast levels can throw off timing for days.