Sourdough · Calculator

Sourdough Starter Feeding Calculator

Set your starter ratio and final target weight to calculate exact seed starter, flour, and water amounts for your next feed — plus how much to discard.

Start calculating Read the guide
Portioned seed starter, flour and water ready for a measured feeding

How to use this calculator

Calculate what to keep, discard and add at the next feeding.

  1. 1

    Set your starter amounts. Enter the mature starter you have and the target weight after feeding.

  2. 2

    Choose a feeding ratio. Pick a preset or enter starter : flour : water parts to match your process.

  3. 3

    Read your feeding amounts. Keep the seed starter shown, discard the excess, then add the calculated flour and water.

Equal flour and water parts make a 100% hydration starter; use different parts to change hydration.

Live calculator · updates as you type

Your feed

g
g
Feeding ratio (starter : flour : water)

Use 100% for an equal-flour-and-water starter. The final hydration includes this retained seed.

Hydration presets calculate the water part using your current seed hydration. Reapply a preset if you change the seed.

Feed with

Add flour 90.9g
Add water 90.9g
Keep seed starter18.2 g
Final hydration100%
Seed starter Flour Water
See your 4 feeding steps

What to do next

Feed your starter in 4 steps

For 200 g of starter at 1:5:5.

  1. 1

    Keep and discard

    1 min

    Keep 18 g of starter and discard 102 g.

  2. 2

    Feed it

    2 min

    Stir in 91 g of flour and 91 g of water (1:5:5).

  3. 3

    Mark the jar

    Now

    Put a band at the level and note the time. At 75°F (24°C), our planning estimate for a 1:5:5 feed is 10–14h to peak. It is an estimate, not a deadline.

  4. 4

    Use it near the top

    At peak

    It may double first and keep climbing. Use it when the rise stalls and the dome is at its highest, before it falls. Some healthy starters top out below double.

Free printable

Keep this batch on one page

A batch card made from your numbers, to save as a PDF or receive by email:

  • Your feeding amounts in big type
  • These steps with tick-boxes
  • Feed and peak times
  • A feeding log to learn your starter

Optional. You can get your PDF without subscribing. Privacy notice.

Before you feed 1:5:5
Keep as seed18.2 g
Discard101.8 g

Discard or use 101.8 g before feeding so you keep only the seed starter needed for this build. Discard is great for pancakes, crackers, and pizza dough.

Feeding ratio estimates at 75°F (24°C)

Ratio (S:F:W) Peak estimate Profile
1:1:1 4–6h Short daily cycle; tangiest
1:2:2 6–10h Moderate daily cycle
1:3:3 8–12h (our extrapolation) Comfortable once-a-day window
1:5:5 10–14h (our extrapolation) Longer interval; milder
1:10:10 14–20h (our extrapolation) Long interval; use an active culture

Planning estimates for an established, healthy 100% hydration wheat starter, not one in its first two weeks. The 1:1:1 and 1:2:2 rows bracket what King Arthur Baking saw at about 78°F, checking every 4 hours; the other cells are our extrapolations. Doubling, the highest point and the first fall are separate moments, and your own starter will vary, so mark the jar and learn its timing. Source: King Arthur Baking, sourdough feeding ratio comparison (2025).

Results use ratio parts by weight. Divide your target starter weight by the total ratio parts, then multiply by each part to get seed starter, flour, and water grams.

New · Featured tool

Sourdough Starter Manager

Log each feed, watch your starter rise in a 3D jar and record when it peaks. After two feeds it learns your own starter’s timing, so you know when it will be ready.

  • See the rise against the clock
  • Learns your starter’s peak time
  • Free, no account needed
Open the starter manager

Starter feeding guide

Choose a ratio, then feed with intent.

Feeding ratio controls how quickly your starter peaks and how acidic it gets before the next feed. Use the calculator above for exact grams, then use this guide to match ratio choice to your schedule.

Ratio is always starter : flour : water by weight. Higher ratios slow the peak — change it live in the calculator below.

How we calculate: Sourdough methods

Use these reference values to interpret your results

  • Fast cycle

    1:1:1

    Best for short intervals and frequent bake-day feeding at room temperature.

  • Balanced cycle

    1:2:2–1:3:3

    A common daily range for stable growth with moderate acidity buildup.

  • Long cycle

    1:5:5+

    Longer feeding windows and slower acid accumulation before peak.

Feeding math

target ÷ total parts

Divide your target starter weight by the total ratio parts, then multiply by each part to get seed starter, flour, and water grams. For 200g at 1:5:5 (11 parts): each part is ~18g, so 18g seed, 91g flour, 91g water.

Worked examples: starter maintenance math

Two numbers drive every feed: how much starter you need and your ratio. Work backwards from the total so you never over- or under-build. The calculator does this for you: divide the target by the total parts, then multiply by each part. For 200g at 1:5:5 (11 parts), each part is about 18g, so 18g seed, 91g flour, 91g water.

FormulaTotal = kept starter × (1 + flour parts + water parts).
1:1:1 from 50g50g + 50g flour + 50g water = 150g.
1:4:4 from 25g25g + 100g flour + 100g water = 225g.
Need 200gKeep about 30g and feed 1:4:4 (120g flour, 120g water) for about 270g: 200g for the dough, about 70g to carry forward.

Choose a feeding schedule and final hydration

Choose a ratio for the interval you can monitor, then use the actual rise to refine that plan. A larger feed provides more food per gram of seed; it does not guarantee an exact peak time.

RatioPlanning peak at 75°F / 24°CExample: seed + flour + water
1:1:14–6h10g + 10g + 10g
1:2:26–10h10g + 20g + 20g
1:5:510–14h10g + 50g + 50g
1:10:1014–20h10g + 100g + 100g

Ranges are estimates for an established, healthy 100%-hydration culture. Custom stiff or liquid builds need their own timing baseline. For final 50% hydration from a 100% seed, 10g seed plus 50g flour needs 22.5g water. Retained seed must be included; a 1:5:2.5 feed does not finish at exactly 50%.

Plan storage and refreshment between bakes, then use readiness observations rather than requiring a float-test pass.

Sourdough starter feeding ratio chart

Ratios are always starter : flour : water by weight, and the times are for 75°F (24°C). Planning estimates for an established, healthy 100% hydration wheat starter, not one in its first two weeks. The 1:1:1 and 1:2:2 rows bracket what King Arthur Baking saw at about 78°F, checking every 4 hours; the other cells are our extrapolations. Doubling, the highest point and the first fall are separate moments, and your own starter will vary, so mark the jar and learn its timing.

My starting point was King Arthur Baking, sourdough feeding ratio comparison (2025), linked under the ratio table in the calculator: at about 78°F, 1:1:1 was near its peak at around 4 hours, 1:2:2 at around 8 and 1:4:4 at around 12. They checked every 4 hours, so the real peaks could fall between checks.

1:1:1Estimate: 4–6h to peak. Tangiest. Daily counter feeding, same-day bakes, reviving a sluggish starter.
1:2:2Estimate: 6–10h. Balanced flavour. Feed at night, use in the morning.
1:3:3Estimate: 8–12h (extrapolated). A comfortable once-a-day window.
1:5:5Estimate: 10–14h (extrapolated). Milder. Long builds, warm kitchens, or a fridge starter waking up for bake day.
1:10:10Estimate: 14–20h (extrapolated). Mildest. Strong starters only, for very long schedules.

What feeding ratios actually control

Each number is a share of the total by weight. A 1:1:1 feed with 20g of old starter takes 20g flour and 20g water; a 1:5:5 feed with 10g takes 50g of each. More food per gram of starter means the culture takes longer to eat through it, so higher ratios peak later. Timing does not scale directly with food quantity; use the same planning ranges throughout this page and learn your culture at a consistent temperature.

Ratio also sets flavour. A low ratio leaves less food per gram of starter, so acid builds faster and the starter tastes tangier; go slightly past peak for a very sour loaf. A high ratio dilutes the acid carried over from the old starter and gives a mild, clean flavour at peak. Using more old starter than the ratio calls for does the opposite: it peaks faster, carries more acid, and collapses sooner after peak.

Which ratio should you use?

There is nothing special about 1:1:1 or 1:5:5; they are just round numbers. Any ratio that fits your schedule works. What matters is consistency: pick one, keep the temperature steady, and learn how your starter behaves so you can plan bakes precisely.

Bake daily1:1:1 on the counter, once a day. Fast, reliable, always ready.
2–3× a week1:2:2 or 1:3:3 on the counter, fed in the evening for a morning bake.
Once a weekKeep it in the fridge; feed 1:5:5, let it peak at room temperature, use it, then return it to the cold.
More tangFeed 1:1:1 and use it slightly past peak.
Less tangFeed 1:5:5 and catch it right at peak.

Hydration and ratio are separate things

The ratio sets the proportions of starter, flour, and water; hydration is the water as a percentage of the flour, which you set with the flour and water parts. Hydration changes handling and fermentation; flavour also depends on flour, temperature, feeding and maturity, so consistency alone does not guarantee an acid profile.

Hydration carries into your dough. 200g of 100% starter is 100g flour and 100g water, which you subtract from the final dough formula so the loaf hits its target hydration.

1:2:3About 140% final hydration with a 100%-hydration seed. Feed water alone would imply 150%, but seed changes the total.
1:2:2100% hydration. The standard: easy to calculate and to read.
1:2:1.6About 84% final hydration with a 100%-hydration seed. Consistency and timing differ from equal feeds.
1:2:160% final hydration with a 100%-hydration seed. Use the target-hydration preset for an exact 50% build.

Temperature and ratio both move the peak

Temperature can move the peak a lot, and so can the ratio: at a steady temperature, going from 1:1:1 to 1:4:4 roughly tripled the time in King Arthur Baking's test. No fixed rule says how much each degree changes it. If the starter peaks too fast or too slow for your day, try moving the jar or changing the ratio, one at a time. A cool kitchen slows it noticeably; on top of the fridge or in an oven with only the light on is often warm enough.

68°F / 20°C1:1:1 estimate: 6–10 hours.
75°F / 24°C1:1:1 estimate: 4–6 hours.
82°F / 28°C1:1:1 estimate: 2–4 hours.

How to tell your starter is at peak

Peak is the highest point the starter reaches in the jar. It is a practical cue, not a measurement of the yeast: the most gas, the most yeast and the most acid do not have to land at the same moment as the highest rise. Mark the level with a rubber band right after feeding and use it when the rise stops and the dome just begins to flatten. Starter used well past peak brings more acid into the dough, so I catch it on the way up or right at the top.

VolumeThe rise has stalled at its highest point. That is often around double, but doubling can come hours earlier and some healthy starters top out below it.
SurfaceDomed top covered in small bubbles, with bubble tracks on the sides.
SmellYeasty and mildly tangy, not sharp, alcoholic, or like acetone.
Float testOptional; stirring, flour and hydration affect buoyancy. It is not a readiness requirement.

Storing your starter between bakes

If you bake once a week or less, keep the starter in the fridge. Feed it, let it rise for an hour or two at room temperature, then refrigerate, and check and refresh it about weekly. Before the next bake, let it warm for an hour and feed it once or twice to wake it up.

For a backup, spread a thin layer on parchment, dry it at room temperature for 24–48 hours, break it into flakes, and store it airtight. Kept completely dry, it lasts for months.

FAQ

Starter feeding questions

Quick answers on starter feeding ratios, discard amounts, and timing.

What is a 1:1:1 sourdough feed?
A 1:1:1 feed means equal parts starter, flour, and water by weight. If you keep 30g starter, feed 30g flour and 30g water.
What is a 1:5:5 feed used for?
A 1:5:5 feed slows acid buildup and gives your starter a larger food supply. It is useful before long room-temperature ferments or when you want a milder starter.
How much starter should I keep before feeding?
Keep only the seed amount required by your target ratio and final weight. The rest can be discarded or used in discard recipes.
Should flour and water always match?
For a 100% hydration starter they match by weight. You can also use different flour and water parts to run stiffer or looser starter builds.
What is the best feeding ratio for sourdough starter?
There is no single best ratio — it depends on your schedule and kitchen temperature. 1:1:1 is the default for daily counter maintenance and peaks fastest (I plan on 4–6 hours at 75°F / 24°C). 1:2:2 or 1:3:3 buys more time and suits a once-a-day feed. 1:5:5 suits a long ferment or a warm kitchen, since the larger food supply slows acid buildup; I plan on 10–14 hours. These are estimates; your own jar sets the real timing.
How often should I feed my sourdough starter?
A starter kept at room temperature needs feeding once or twice a day, depending on ratio and warmth. A starter stored in the fridge only needs feeding about once a week. Feed more often (or at a higher ratio) in a warm kitchen, because heat speeds fermentation and the culture runs through its food faster.
Should I feed my starter by weight or by volume?
Always by weight. Cups of flour vary enormously depending on how packed they are, so volume feeds give inconsistent ratios and unpredictable peak times. A cheap digital scale in grams is the single best tool for a reliable starter — set the ratio you want and the numbers stay consistent every feed.
What ratio should I use to slow my starter down?
Feed at a higher ratio — 1:5:5 or even 1:10:10. Giving the culture much more flour and water relative to the existing starter means it takes far longer to consume the food and peak, so you can stretch the gap between feeds or hold it closer to bake time without it going over. Cooler storage slows it further.
Can I use a 1:10:10 ratio?
Yes, but only with a healthy, active starter. A weak or sluggish culture cannot work through that much food and will peak poorly, so build up to high ratios gradually. At 75°F / 24°C my rough estimate for a strong starter fed 1:10:10 is 14–20 hours, extrapolated rather than measured.
Why does my 1:5:5 starter taste milder than my 1:1:1?
The large food supply dilutes the acid carried over from the old starter, so the culture is milder at peak. A 1:1:1 feed has less food per gram of starter, builds acid faster, and tastes tangier. For more tang at 1:5:5, let it go a little past peak before using it.
How much does temperature change starter peak time?
A lot, and so does the ratio. For a 1:1:1 feed I plan on about 6–10 hours at 68°F / 20°C, 4–6 hours at 75°F / 24°C and 2–4 hours at 82°F / 28°C. These are estimates; there is no fixed rule for how much each degree changes it, so watch your own jar at a steady temperature.
What is starter hydration and how does it change the feed?
Hydration is water as a percentage of flour in the starter. Equal flour and water parts make a 100% starter, the pourable standard. Less water makes a stiffer starter; more makes a looser one. Flavour and timing also depend on flour, temperature and feed maturity. The calculator includes retained-seed hydration and final-hydration build presets.
When is sourdough starter ready to use?
When the rise has stalled at its highest point, the top is domed and bubbly, and it smells yeasty and mildly tangy rather than sharp. Doubling often comes before that, and some healthy starters top out below double. The float test is optional and depends on flour, hydration and handling. Mark the level with a rubber band right after feeding and use it when the rise stops and the dome just begins to flatten.
Why is my sourdough starter not rising?
The usual causes are cold, hunger, or excess acid. Move it somewhere warmer (24–28°C), feed it twice a day at 1:1:1, and discard down to 20–30g so acid does not build up. Adding a little whole wheat or rye to the feed reboots a sluggish culture. A starter under two weeks old also naturally goes quiet after an early false rise, so keep feeding through it.
Can I feed my starter without discarding?
Not indefinitely. If you never discard, the jar grows exponentially and the acidity climbs until it inhibits the yeast. You can skip discarding for a feed or two to build volume for a big bake, but for routine maintenance keep only 20–50g and feed that. The discard calculator turns what you remove into pancakes, crackers, and other recipes.
What is the difference between a starter and a levain?
The starter is the ongoing culture you keep and feed. A levain is a separate build of starter, flour, and water made for one recipe and timed to peak at mixing. This calculator handles feeding the main jar; the levain calculator sizes a recipe build.

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