How to feed sourdough starter and choose the right ratio

How to feed sourdough starter, in short: weigh a small amount of old culture into a clean jar and stir in fresh flour and water. 20g starter, 20g flour, 20g water is a standard 1:1:1 feed. The ratio doesn't make the culture stronger — it sets when the starter peaks.

What a sourdough starter ratio actually means

The three numbers are starter : flour : water, always by weight. 1:1:1 is equal parts of each. 1:5:5 is one part old starter to five parts each of fresh flour and water. Volume doesn't work here — a cup of water weighs roughly twice what a cup of flour does, so a "cup for cup" feed is nowhere near 1:1:1.

Most home cultures run at 100% hydration, meaning the water and flour weigh the same, which is why those last two numbers usually match. Shift to 1:2:1 and you have a stiff starter: slower, more acetic, a different schedule.

The first number does the work. It's the seed — the amount of already-fermented culture carried into the fresh flour. A big seed means a crowded jar at hour zero and a fast climb. A small seed means the population has to build before it can eat, which stretches the timeline. If you're still building a starter from scratch, get it doubling predictably on a 1:1:1 before you start playing with ratios.

How to feed sourdough starter, step by step

1. Put the jar on a scale and tare it. Everything downstream depends on weight.
2. Take the jar down to your seed. For a 1:1:1 feed with a 20g seed, remove everything above 20g. That surplus is the discard.
3. Add flour and water. 20g flour, 20g water for 1:1:1. Water around 80–90°F gets things moving a little faster; water much above 120°F starts killing yeast.
4. Stir until no dry flour remains, then scrape the sides down so you can read the rise cleanly.
5. Mark the level. A rubber band around the jar or a dry-erase line is the only honest way to know what "doubled" looked like.
6. Cover loosely and leave it somewhere with a stable temperature.

Then leave it alone. Stirring mid-rise resets the visual clock you just set.

The sourdough starter feeding ratio is a time dial

You don't pick a ratio because one is more correct than another. You pick the one that puts peak where you need it in the day.

At around 75°F, a 1:1:1 feed peaks in roughly 4–6 hours. Move to 1:2:2 and it's 6–8. Go to 1:5:5 and you're looking at 10–12 — long enough to feed at 9pm and find a ripe starter at breakfast. Same culture, same flour, same jar. Only the seed changed.

Temperature is the second dial, and it's a strong one. Warmer rooms move peak earlier and colder ones push it later, as the table below shows. The relationship isn't perfectly linear and the inside of the jar lags the room, but the direction is dependable.

Feeding ratio	65°F / 18°C	70°F / 21°C	75°F / 24°C	80°F / 27°C
1:1:1	6–9 hrs	5–7 hrs	4–6 hrs	3–5 hrs
1:2:2	9–12 hrs	7–10 hrs	6–8 hrs	5–7 hrs
1:5:5	15–18 hrs	12–15 hrs	10–12 hrs	8–10 hrs
1:10:10	21–24 hrs	17–20 hrs	14–16 hrs	11–13 hrs

Treat those as starting estimates. Whole rye or whole wheat will noticeably shorten any cell in the table, and a starter under a month old runs slower than a mature one.

Reading peak in your own jar

Peak is the moment the rise stops and the surface goes from domed to flat, just before it sinks and leaves drag marks on the glass. Most white-flour starters at 100% hydration roughly double or triple. The float test is unreliable at higher hydration — a wet starter can sink even at perfect ripeness — so trust the mark on the jar instead.

The ratio-to-peak times above are averages across cultures, flours, and kitchens. A week of logged feeds and peaks in Sourdough Tracker, a sourdough baking companion app for iPhone, gives you your own starter's actual clock instead of a table's.

How often to feed sourdough starter

On the counter, a starter fed 1:1:1 wants feeding once or twice a day, because it hits peak early and then sits collapsed, burning through what's left. Twice daily at 1:1:1 keeps it at its liveliest. Once daily works better at 1:3:3 or wider, so peak lands closer to the next feed.

In the fridge, once a week is a normal sourdough starter feeding schedule. Cold doesn't stop fermentation, it slows it to a crawl. The routine is: pull the jar out, feed it, let it get going at room temperature for an hour or two, then put it back cold.

Miss a week — or three — and it usually still comes back. A dark liquid layer on top, hooch, means hungry, not dead. Pour it off for a milder result or stir it in for more tang, then run two or three consecutive 1:1:1 feeds at room temperature. If it's doubling on schedule by the third, it's ready to bake with. Fuzzy pink, orange, or black growth is the one exception: that jar goes in the trash.

Maintenance feed vs. pre-bake build

These are two different jobs, and treating them as one is why people end up with enormous jars.

A maintenance feed keeps the culture alive between bakes. It should be small — 10 to 20g of seed is plenty — and the ratio only has to be wide enough that the starter isn't sitting collapsed for hours before you get back to it.

A pre-bake build, or levain, makes the specific quantity your recipe calls for, timed to peak when you want to mix. Most loaves call for 100–200g. From a 20g seed, a 1:5:5 build gives you 220g in 10–12 hours at room temperature, which puts the feed the night before a morning mix.

You can build in stages. If your maintenance jar is tiny and the recipe needs a lot of levain, do a 1:2:2 in the afternoon and a 1:5:5 that evening rather than one enormous jump.

How much to feed sourdough starter: shrink the jar, shrink the discard

Discard is a size problem, not a technique problem. At steady state, every feed removes whatever grew past your seed. Maintain 100g and feed it 1:1:1 daily and you throw out 200g of flour and water a day. Maintain 20g and the same feed makes 60g, of which 40g leaves the jar.

Keep that 20g jar in the fridge on a weekly schedule and 40g a week is the entire cost — about three tablespoons. Drop the seed to 10g and it's half that. A 20g culture isn't a weaker culture. What matters is the density of yeast and bacteria per gram, and that doesn't change with jar size.

Two other routes to near-zero: time the maintenance feed so the whole jar becomes the levain for a bake, or keep a discard jar in the fridge for crackers and pancakes, where unfed starter is an ingredient rather than a leavener.

Flour and water: the two dials nobody adjusts

Whole grain ferments faster than white — more of the minerals and enzymes the culture wants, plus more wild yeast on the bran. Swapping even 20% of a feed to whole rye visibly shortens peak time. Bleached all-purpose works, but it's noticeably sluggish.

Chlorinated tap water is usually fine; municipal levels aren't enough to stall a healthy culture. If yours is heavily treated, use filtered. Skip distilled water long term — the culture uses the minerals that got distilled out.

FAQ

How often should I feed my sourdough starter?

Once or twice a day at room temperature, or once a week in the fridge. The signal is peak: if it's collapsing hours before the next feed, either feed more often or widen the ratio so it takes longer to get there.

What's the best sourdough starter feeding ratio?

There isn't one — pick by timing. 1:1:1 for a same-day bake, 1:2:2 for a morning-to-evening gap, 1:5:5 for overnight. All three produce the same culture; they just peak at different hours.

Do I have to discard sourdough starter every time?

Only if the jar is growing past the size you want to keep. With a 10–20g seed the surplus is a spoonful or two. Discard exists to control volume and acidity, not because the removed portion has gone bad.

How do I know my starter is ready to bake with?

It should reliably double or better within the window its ratio and temperature predict, smell tangy and yeasty rather than sharply solvent-like, and hold a domed top at peak. Two or three predictable cycles in a row is the real test.

How to maintain a sourdough starter if I only bake once a month?

Keep it cold and keep it small. Feed once a week when you can; if you skip, it will usually survive several weeks in the fridge anyway. Plan two or three room-temperature feeds in the days before a bake to bring it back to full strength.