Sourdough Starter Feeding Calculator
Calculate starter, flour and water from your feeding ratio, a bake quantity plus reserve, or the starter you retain.
Your feed by weight
- Retained starter
- 35 g
- Add flour
- 70 g
- Add water
- 70 g
- Total after feeding
- 175 g
Fresh feed hydration: 100%. Final mixture hydration, including retained starter: 100%.
Calculated before jar losses. Displayed weights are rounded to 0.01 g; use the precision your scale supports and keep the proportions as close as practical. This ratio does not predict the peak time.
The calculation
One part = (starter needed + reserve) ÷ (starter parts + flour parts + water parts).
Worked example
For 150 g in your recipe plus 25 g reserve at 1:2:2, one part is 175 ÷ 5 = 35 g. Retain 35 g starter and add 70 g flour and 70 g water for 175 g total.
What to check
A feeding ratio sets the weights, not the time to peak. Temperature, flour and the condition of the seed starter affect activity. These weights assume no jar losses.
Read the method
By Crispy Crust · Published 10 November 2026 · How we write and review guides