Sourdough Starter Ratios

Remember back to your 6th grade math class? You know, the one where you learned about ratios and thought you would never use them again. Well, maybe that was just me, but I was proved wrong as soon as I started mixing and baking sourdough! Here’s the thing, ratios are actually a really important part of bread recipes and especially sourdough recipes. So let’s talk sourdough starter ratios. Why are the ratios you use to maintain a sourdough starter important? How can you use them to help your sourdough baking? It’s not scary. It’s just a little bit of math and you’ve got this!

What is a Sourdough Starter Ratio?

A ratio is a term used to compare two or more numbers. In baking we compare every ingredient to the weight of the flour in a recipe. This is also true for sourdough. When we maintain a sourdough starter with frequent feedings, we express the amount fed in a ratio; the weight of the starter to the flour and the water. Since sourdough starter is a living organism, it requires food (flour) to stay active and healthy. The amount of flour you provide directly influences when the starter will peak and be ready for use. ⁠

A sourdough starter is maintained by taking a portion of the inactive starter and feeding it flour and water. This feeding is often expressed as a ratio, comparing the weight of the starter, flour and water.

Why are Sourdough Ratios Important?

Let’s take a look at your sourdough starter. Sourdough starters should be fed a minimum ratio of 1:1:1, meaning equal WEIGHTS of starter to flour to water. If you feed your starter this way and keep it at a consistently warm temperature 78ºF, your starter should peak and become active/bubbly in about 3-4 hours. But, we may not always want our starter to be ready in 3-4 hours. For example, you may want your starter to be ready 10-12 hours after feeding it in the evening. In order for our starter to be ready in that amount of time, we can either adjust the temperature (decreasing the temperature of the starter will significantly slow it down) OR adjust the amount of flour we are feeding the starter.

The more starter that you carryover compared to the flour and water that you feed it with, the quicker the starter will peak. The less starter you carryover and feed, the longer it will take for a starter to peak.

Making a Sourdough Starter Work for You

I’m a big believer in working smarter – not harder! You shouldn’t be twiddling your thumbs waiting for your starter to peak. Instead, decide what time you want to use your starter. From that, figure out the ratio you need to feed your starter to have it ready when you want it ready.

The table below shows examples of ratios used to feed a starter. Assuming 78ºF temperature, and a healthy/active sourdough starter fed primarily with bread flour or all-purpose flour, the table shows the time it will take for a starter to reach its peak and when it needs to be refreshed. Watch a video example of this process here.

RatioExample in Grams assuming 78ºFRipe/Reaches Peak/
Make Levain
Need refreshing
1:1:110 grams ripe starter
10 grams flour
10 grams water
3-4 hours7-8 hours
1:2:210 grams ripe starter
20 grams flour
20 grams water
5 hours10 hours
1:5:510 grams ripe starter
50 grams flour
50 grams water
6-7 hours12-14 hours
1:10:1010 grams ripe starter
100 grams flour
100 grams water
10-12 hours24 hours

Maintaining a Healthy Sourdough Starter Using Ratios

The more you feed and refresh your sourdough starter, the more active and healthy it becomes. Changing up the ratios you feed your starter can also make your starter more resilient. My number one reason for knowing the ratios I’m feeding my starter, is because it allows me to plan out my bakes. I’m never wondering when my starter will be ready. I know when it will be peaked and active because I’m maintaining the temperature and feeding it a certain ratio. This is priceless in sourdough baking!

Can I use ratios with a Levain too?

Yes! Create a levain using the same ratio table as starter. If a recipe calls for 120 grams of levain, you can feed a 1:10:10 ratio (6 grams starter, 60 grams flour and 60 grams water), a 1:1:1 ratio (40 grams starter, 40 grams flour and 40 grams water) or any ratio you wish. It will take more or less time depending on your temperature and feeding ratio.

I always seem to lose some of the weight of my levain or starter during feeding. Why?

When I calculate how much levain to make in a recipe, I always mix up a little bit extra because some of the weight of the levain (or starter) is lost during the fermentation cycle (usually about 2% of the weight). If you lose some and don’t have extra, it’s okay. Just proceed with your recipe and give it a little extra time to ferment.

Always remember, you are in control of your sourdough starter! Don’t let it control you! Know your ratios. Experiment with feeding different amounts of flour and water to your starter and watch the change in your baking – it will get easier and it will get better.

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