A 1:2:2 sourdough starter feed is a ratio of existing starter : fresh flour : fresh water, measured by weight. It gives you ingredient quantities, not a fixed fermentation time.
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See how 10g of starter becomes 50g of fed starter, then scale the same ratio to a larger batch.
The three numbers, in order
- 1 part existing starter — the portion you keep for this feed.
- 2 parts flour — twice the weight of that starter portion.
- 2 parts water — also twice the starter portion's weight.
A simple 50g feed
- Put a jar on your kitchen scale and tare it to zero.
- Weigh in 10g of starter.
- Add 20g of flour and 20g of water. Weigh each addition separately, or use cumulative readings of 10g, 30g and 50g.
- Stir together. You now have 50g of fed starter. Mark its starting level and observe the rise.
Make the batch size you need
| Starter | Flour | Water | Total |
|---|---|---|---|
| 10g | 20g | 20g | 50g |
| 15g | 30g | 30g | 75g |
| 20g | 40g | 40g | 100g |
The ratio has five parts in total. Divide your desired total by five to find the starter portion, then double that amount for both flour and water.
The common mistake: reading the ratio as a clock
1:2:2 does not mean waiting two hours. Temperature, flour and starter activity affect when it peaks. Follow your recipe and your starter's behaviour rather than assuming one universal waiting time.
Weigh the feed, then watch the rise.
For more on feeding ratios and their effect on timing, see King Arthur Baking's feeding-ratio trials. Explore more KNEVA baking guides.