Sourdough Starter Feeding Calculator
Choose your feeding ratio and how much fed starter you need.
Include enough to bake with plus some to keep going.
Answer
30g starter + 60g flour + 60g water
The feed
Next step
Worth knowing
- Keep 30g of your existing starter and discard or use the other 70g before feeding.
- A good overnight feed, ready to use in the morning.
- Feed by weight, not by spoonfuls. Scales are the difference between a predictable starter and a temperamental one.
- A starter is ready to bake with when it has roughly doubled, domed on top and smells tangy rather than sharp.
- Warmth speeds everything up. In a cold kitchen the same feed can take twice as long to peak.
Source: Baker's percentage method, standard UK bread and pizza formulations · Reviewed 2026-09-10 · Guidance version 1.0.0
Reference and detail
The ratio sets the timing
A 1:1:1 feed peaks in a few hours; a 1:5:5 feed takes much longer because there is far more flour for the same amount of culture to work through. Pick the ratio to suit when you want to bake.
Keep less starter than you think
Most home bakers keep far too much and throw most of it away. Fifty grams in the jar is plenty, build up the amount you need the night before.
Use it at its peak
Domed, bubbly and just starting to flatten is the moment. A starter that has collapsed has run out of food and will lift your loaf slowly if at all.
Questions and answers
Questions about feeding a sourdough starter
What does a 1:2:2 feeding ratio mean?
It's the ratio of starter to flour to water by weight, one part of your existing starter to two parts fresh flour and two parts water. Choose the ratio above and the calculator scales it to however much fed starter you want to end up with.
Should I feed my starter by weight or by spoonfuls?
By weight. Scales give a predictable, repeatable starter; spoonfuls vary enough from feed to feed that the starter's behaviour becomes unpredictable.
How do I know when my starter is ready to bake with?
It's ready when it has roughly doubled in size, domes on top, and smells tangy rather than sharply acidic. Warmth speeds this up considerably, so the same feed can peak much faster in a warm kitchen than a cold one.
What do I do with the discard when I feed my starter?
Keep the amount of existing starter the calculator says to keep, and either discard the rest or use it in a discard recipe such as pancakes or crackers.