Sourdough Hydration Calculator
Enter your flour, target hydration and starter details to see the water to add and your dough's true hydration once the starter is included.
70% is a forgiving starting point. 80% and above needs confident handling.
Fed with equal weights of flour and water? That is 100%.
Answer
Add 335g of water
Weigh out
What to do
- 1Mix 500g flour with 335g water and leave for 30 minutes.
- 2Add 100g of active, bubbly starter and work it in.
- 3Add 11g salt and mix until the dough feels smooth and elastic.
- 4Fold every 30 to 45 minutes for 3 to 4 hours, then shape and prove in the fridge overnight.
Next step
Worth knowing
- The flour and water inside your starter count towards the dough. This calculator takes them out of the water you add, which is why real hydration and recipe hydration are often different.
- Higher hydration means an open crumb but a slacker, stickier dough. If you are new to sourdough, 70% is a forgiving place to start.
- Wholemeal and rye flours absorb more water, so the same percentage feels drier with them.
Source: Baker's percentage method, standard UK bread and pizza formulations · Reviewed 2026-09-10 · Guidance version 1.0.0
Reference and detail
Your starter is flour and water too
A 100% hydration starter is half flour, half water by weight. Ignoring that is why a dough aiming at 70% often behaves like a much wetter one.
Hydration describes how the dough handles
Around 65 to 70% is manageable by hand and holds a shape. Above 80% the dough is slack and sticky and needs confident folding and a well-proved starter.
Flour changes what a number feels like
Strong white, wholemeal and rye all absorb different amounts of water. Treat the percentage as a starting point and adjust by feel next bake.
Questions and answers
Questions about sourdough hydration
What does 70% hydration mean for sourdough?
It means the total water in the dough weighs 70% of the total flour weight, so 500g flour worth of water would be 350g. It's a useful starting point for anyone new to sourdough, giving a dough that's workable without being overly sticky.
Does the starter count towards the dough's hydration?
Yes. Your starter is itself a mixture of flour and water, and both parts count towards the dough's true hydration, not just the water you add at the mixing stage. This calculator splits the starter into its flour and water and works out how much water to actually add to hit your target.
Why is my dough's real hydration different from the percentage in the recipe?
Because the recipe percentage and the true hydration only match if the starter's own hydration happens to match the dough's. Enter your starter's hydration above and the calculator shows both the water to add and the true hydration once the starter is accounted for.
Why does wholemeal or rye flour need a different hydration?
Wholemeal and rye flours absorb more water than white bread flour, so a dough at the same percentage feels noticeably drier with them. Treat the same hydration figure as a starting point and adjust by feel.
What hydration should a beginner start with?
Around 70% is a forgiving starting point, wet enough for a decent open crumb, but not so slack that it's difficult to handle by hand.
Guidance
Read the full guide
- Understanding Dough HydrationWhat a hydration percentage means, why sourdough is counted differently once a starter is involved, and how baker's percentage ties the whole formula together.