A 100% hydration sourdough starter is the most commonly used type in bread recipes. It is easy to maintain and works well with most sourdough baking.
In this guide, you will learn about starter hydration, the various hydration levels, and how to adjust them.
What is sourdough starter hydration?
Sourdough starter hydration refers to the ratio of liquid (usually water) to flour. It is expressed as a percentage and affects the consistency or thickness of your starter.
- A higher hydration level means your starter is more liquid and runny.
- A lower hydration level means your starter is firmer and dough-like.
This balance impacts how your starter ferments and affects the final flavor and texture of your bread.
Types of sourdough starter hydration
For beginners, I highly recommend using a 100% hydration starter, which is the standard in sourdough baking. If a recipe does not specify the hydration level, it typically assumes a hydration level of 100%.
Here are the three main types of starter hydration:
- 100% hydration starter: Equal weights of water and flour.
- Lower hydration starter (below 100%): More flour than water, creating a stiff, dough-like starter.
- Higher hydration starter (above 100%): More water than flour, resulting in a liquid, pancake batter-like consistency starter.
How to make a 100% hydration starter
To make and maintain a 100% hydration starter, feed it with equal weights of flour and water (by weight).
For example:
- If you have 20 grams of starter, you would feed it 20 grams of water and 20 grams of flour. This keeps the water-to-flour ratio at 1:1 by weight.
- If you have 5 grams of starter, you could feed it 30 grams of water and 30 grams of flour. This still results in a 100% hydration starter, as the weights of water and flour are equal (30g of water = 30g of flour).
Use a pocket gram scale for this process. Measuring by weight, not volume, provides the best accuracy and consistency in your starter.
How to adjust your sourdough starter hydration
Changing your starter hydration is simple but requires precision and patience. Use a digital scale to measure carefully. Minor changes to the water-to-flour ratio can make a big difference.
For example, adding 10-30% whole-grain flour, like whole wheat or rye, can affect hydration because these flours absorb more water.
Experiment with different flours and hydration levels to create a starter that best suits your bread and personal taste. However, I recommend sticking to the basics if you are starting out.
Let's talk sourdough
Have you started a 100% hydration starter yet? What surprised you most about the process? Share your story in the comments.
Ready to keep learning?
Your starter's hydration is set. Now it is time to learn how much to feed it. Master sourdough starter feeding ratios to keep your culture healthy and predictable.
Marney Peek says
Great information on hydration. Just starting back into sourdough now but allergic to gluten for the past 15+ years. Have been experimenting with my gluten free starter (yes that has been a journey) and different flours. They are not all equal in my experience.
This information has been helpful. Any comments on GF sourdough would be great. Thank you!
Irina Totterman says
Hello Marney, thank you for your comment. At the moment, I don’t work with gluten-free sourdough, so I’m unable to provide detailed information on that.
Margaret Little says
I’m new to sourdough basics. How much of my starter do I remove and how often? It’s not all that clear.
Irina Totterman says
Hello Margaret, you’ve landed on a blog post devoted to sourdough starter hydration. Please check out how to feed a sourdough starter and sourdough starter feeding ratios.
Susan says
Do I discard every time I feed my starter?
Irina Totterman says
Hello Susan, yes, you do need to discard some starter before each feeding and refresh it with fresh flour and water. This keeps the starter balanced and healthy. Please, check out why discarding sourdough starter is necessary. However, there are ways to maintain a starter with no discard.
Paula S Rovinsky says
Hi. Very grateful for this information and link as just starting out making sourdough breads. You mentioned above for 100% hydration use equal amounts of flour and water. In the example of 5 grams of starter, you wrote"you could use 30 grams flour, 30 grams water. Could you use less or more ( say if needed more starter) as long as it was equal? So say 15 grams or 50 grams of each flour and water? If using a mix of whole wheat and bread flour how much more water would need to be added for proper hydration ration?
Irina Totterman says
Hello Paula, A 100% hydration sourdough starter means it contains equal amounts of flour and water by weight. This is different from the feeding ratio. In my example, I used 5 g of starter with 30 g of flour and 30 g of water. The starter remains at 100% hydration because the flour and water are equal. The feeding ratio in that case is 1:6:6.
You can adjust the amounts depending on how much starter you need, as long as the flour and water remain equal to maintain 100% hydration. For example, if you use 15 g of starter, you could add 50 g of flour and 50 g of water. However, that would create a feeding ratio of about 1:3.3:3.3, which is a bit unusual. It is more common to use whole-number ratios such as 1:3:3 or 1:4:4 because they are easier to calculate and keep consistent.
If you are using a mix of whole wheat and bread flour, for example 10–20% whole wheat and 80–90% bread flour, you do not need to change the hydration. The starter may feel slightly thicker since whole wheat absorbs more water, but keeping it at 100% hydration makes calculations much simpler.