Sourdough Starter Ratio Calculator.
Enter how much starter you need and how soon you want it ready. You get the feeding ratio and the exact amounts of old starter, flour and water to weigh out.
What you want to end up with
g
Picks the ratio for you
A rough guide for a kitchen around 75 °F (24 °C). Cooler is slower, warmer is faster.
Feeding ratio
Feed this
How it works
What a starter ratio means
A feeding ratio such as 1:5:5 lists parts by weight of old starter, flour and water. The bigger the flour and water numbers compared with the old starter, the more food each bit of starter gets, so it takes longer to peak.
a : b : c = starter : flour : water parts = a + b + c Old starter = total × a ÷ parts Flour = total × b ÷ parts Water = total × c ÷ parts
- Total is everything you end up with: old starter, flour and water together.
- Ready in about chooses the ratio. A bigger ratio peaks later, so it suits a longer wait.
Worked example
Making 550.0 g of starter at 1:5:5, ready in about 10–12 hours.
| Old starter | 50.0 g |
| Flour | 250.0 g |
| Water | 250.0 ml |
| Total starter | 550.0 g |
Rules of thumb
Which ratio should I use?
Approximate time to peak in a kitchen around 75 °F (24 °C). Cooler is slower, warmer is faster.
| Ratio | Good for | Peaks in about |
|---|---|---|
| 1:1:1 | Quick refresh of a small or sluggish starter | 4–6 hours |
| 1:2:2 | Everyday feeding on the counter | 6–8 hours |
| 1:3:3 | Feeding in the evening or before a daytime bake | 8–10 hours |
| 1:5:5 | Overnight builds and levain for a bake | 10–12 hours |
| 1:10:10 | Long, slow builds and fridge-kept starters | 12–16 hours |
FAQ
Starter ratio questions
What does a 1:2:2 starter ratio mean?
The three numbers are parts by weight of old starter, flour and water. At 1:2:2 you feed 1 part of your starter with 2 parts flour and 2 parts water. For example, 50 g of starter plus 100 g of flour and 100 ml of water makes 250 g.
Which feeding ratio should I use?
It depends on how soon you want the starter ready. Low ratios such as 1:1:1 or 1:2:2 peak in a few hours and suit daily feeding in a warm kitchen. High ratios such as 1:5:5 or 1:10:10 give each bit of starter more food, so it peaks later and fits an overnight build or a fridge-kept starter.
How does the “Ready in about” picker work?
Choose how long you are happy to wait and the calculator picks the feeding ratio that usually gets a starter there: 1:1:1 for about 4–6 hours, 1:2:2 for 6–8 hours, 1:3:3 for 8–10 hours, 1:5:5 for 10–12 hours and 1:10:10 for 12–16 hours. The times are estimates for a kitchen around 75 °F (24 °C). If you type your own ratio, the picker switches to “Custom ratio”.
How long does a starter take to peak at each ratio?
Roughly 4–6 hours at 1:1:1, 6–8 hours at 1:2:2, 8–10 hours at 1:3:3, 10–12 hours at 1:5:5 and 12–16 hours at 1:10:10, in a kitchen around 75 °F (24 °C). These are guides only. A cooler room is slower, a warmer one faster, and a strong, well-established starter peaks sooner than a young one.
How do I use the amounts if I already have some starter?
Enter the total amount of starter you want to end up with. The calculator tells you how much of your existing starter to use (the “Old starter” amount), plus the flour and water to add to it. For example, 50 g of old starter, 100 g of flour and 100 ml of water makes 250 g.
Can I use my own ratio?
Yes. Choose “Custom ratio” in the picker, or just change the Seed, Flour and Water numbers under it, and type any ratio you like, such as 1:3:3. The amounts update as you type, and the picker stays on “Custom ratio” until you choose a time again.
What is the starter to flour ratio when I feed 1:5:5?
It is 1 part starter to 5 parts flour, with 5 parts water, all by weight. For example, 20 g of starter with 100 g of flour and 100 ml of water. That is different from the starter percentage in a recipe, which compares the starter with the flour in the dough. The sourdough calculator on the home page handles that one.
Does the feeding ratio change my starter’s hydration?
Not with the ratios in the picker. They all use equal weights of flour and water, so a starter fed that way stays at 100% hydration. The calculator assumes your starter is fed this way, which is the most common. A stiffer or wetter starter gives the same amounts, but the finished starter will be a little stiffer or wetter.
Is the feeding ratio the same as the starter percentage in a recipe?
No. The feeding ratio describes how you build or refresh the starter. The starter percentage in a recipe describes how much of that starter goes into the dough, as a share of the total flour. The main sourdough calculator handles the second one.
Next step
Ready to bake?
Once your starter is fed, the sourdough calculator works out the flour, water, starter and salt for the loaf, with the flour and water in your starter already counted.