Sourdough Hydration Calculator
Instant baker's % math

Dial in sourdough hydration, starter, salt — and get exact grams.

Choose a target dough weight or total flour. Adjust hydration, salt, and starter (including starter hydration). The recipe updates live, and you can copy or print a clean formula for the bench.

Calculator
Enter your inputs. Results update live; use Calculate to log an analytics event.
Scale multiplies all ingredient weights (effective hydration stays the same).
Starter breakdown: 58.1 g flour + 58.1 g water
Results
These are the weights to add for your chosen inputs.
Flour to add
523.3 g
Water to add
348.8 g
Starter
116.3 g
Salt
11.6 g
Total dough weight
1,000 g
Effective hydration
70%

Tips

Starter hydration matters

A 100% starter is half flour / half water by weight. A stiffer starter contributes less water, so your added water changes.

Negative added water?

That usually means your starter already contains more water than the formula allows. Reduce starter, increase hydration, or increase total flour.

Salt defaults

Many sourdough formulas sit around 2% salt. Adjust to taste.

Scaling

Use scale to multiply your batch for multiple loaves without redoing the math.

FAQ

What is hydration?

Hydration is water weight divided by flour weight (×100). A 70% dough has 70g water for every 100g flour (including the starter).

What does “starter % of flour” mean?

It’s starter weight relative to total flour weight. Example: 20% starter on 500g flour means 100g starter.

Why is my added water negative?

Your starter contributes water. If starter water exceeds total water required for your hydration, the “water to add” becomes negative. Reduce starter, increase hydration, or increase flour.

How do I scale batches?

Set the Scale multiplier. It multiplies all ingredient weights and total dough weight. Hydration percentage stays the same.

Does starter hydration matter?

Yes. Stiff starters (lower hydration) contribute more flour and less water; liquid starters do the opposite.