What goes in my sourdough?
Type how much flour you want to use, or how much dough you want to end with, and the hydration, starter and salt percentages. The sourdough calculator works out the flour and water to add, the starter and the salt, using baker's percentages that count the flour and water in the starter.
- Flour to add
- 450 g
Mix 450 g flour, 300 g water, 100 g starter and 10 g salt.
- Water to add
- 300 g
- Starter
- 100 g
- Salt
- 10 g
- Total flour
- 500 g
- Total water
- 350 g
- Dough weight
- 860 g
Flour to add: 450 g. Mix 450 g flour, 300 g water, 100 g starter and 10 g salt.
How to calculate
Works out a sourdough recipe from baker’s percentages: the flour, water, starter and salt to mix for a hydration you choose, counting the flour and water already in the starter.
Example with the default inputs (Start from Total flour, Total flour 500 g, Hydration 70%, Starter 20%, Salt 2%, Starter hydration 100%): Mix 450 g flour, 300 g water, 100 g starter and 10 g salt.
Method: Total water = hydration × total flour; starter = starter % × total flour; salt = salt % × total flour. The starter holds starter ÷ (1 + starter hydration) of flour and the rest water, so flour to add = total flour − starter flour and water to add = total water − starter water. From a dough weight D, total flour = D ÷ (1 + hydration + salt).
- Every percent is of the total flour, including the flour in the starter (baker’s percentages).
- The starter is only flour and water, at the starter hydration you give (100% means equal weights).
- Weights are as mixed; water lost in baking is not modelled.
Worked examples
Each example is checked against the calculator on every build.
- Start from Total flour, Total flour 500 g, Hydration 70%, Starter 20%, Salt 2%, Starter hydration 100% gives Flour to add 450 g, Water to add 300 g, Starter 100 g, Salt 10 g, Dough weight 860 g.Source: Wikipedia, Baker percentage (each ingredient as a percent of the flour weight; the water percent is the hydration; flour weight = dough weight ÷ the sum of the percentages), https://en.wikipedia.org/wiki/Baker_percentage (retrieved 2026-10-02)
- Start from Dough weight, Dough weight 900 g, Hydration 75%, Starter 20%, Salt 2%, Starter hydration 100% gives Total flour 508 g, Water to add 331 g, Dough weight 900 g.Source: Wikipedia, Baker percentage (each ingredient as a percent of the flour weight; the water percent is the hydration; flour weight = dough weight ÷ the sum of the percentages), https://en.wikipedia.org/wiki/Baker_percentage (retrieved 2026-10-02)
- Start from Total flour, Total flour 1,000 g, Hydration 65%, Starter 30%, Salt 2.2%, Starter hydration 50% gives Flour to add 800 g, Water to add 550 g, Starter 300 g, Salt 22 g.Source: Wikipedia, Baker percentage (each ingredient as a percent of the flour weight; the water percent is the hydration; flour weight = dough weight ÷ the sum of the percentages), https://en.wikipedia.org/wiki/Baker_percentage (retrieved 2026-10-02)
How it works
Every percent is a baker's percent of the total flour F, which includes the flour in the starter. With hydration h, starter s, salt c and starter hydration r (all as fractions, 70% = 0.70):
- total water W = h × F; starter weight S = s × F; salt = c × F
- the starter holds S ÷ (1 + r) of flour and S − S ÷ (1 + r) of water
- flour to add = F − S ÷ (1 + r)
- water to add = W − (S − S ÷ (1 + r))
- dough weight = F + W + salt = F × (1 + h + c), because the starter's flour and water are already in F and W
- from a dough weight D: F = D ÷ (1 + h + c)
Weights are converted to kilograms first (1 oz = 28.349523125 g, 1 lb = 453.59237 g); the maths runs in double precision.
Rules
- Flour or dough weight 1 g to 1,000 kg. Hydration 0% to 200%, starter 0% to 100%, salt 0% to 10%, starter hydration 0% to 500% (default 100%).
- If the starter holds more water than the dough's total water (water to add below 0), there is no answer. A water-to-add within 10⁻¹² of the flour weight of 0 is shown as 0.
Output format. Every weight in grams, rounded to a whole gram.
Worked examples by hand
500 g flour, 70% hydration, 20% starter at 100%, 2% salt. Starter 0.20 × 500 = 100 g (50 g flour + 50 g water). Total water 0.70 × 500 = 350 g. Add 450 g flour and 350 − 50 = 300 g water; salt 10 g. Dough 500 × 1.72 = 860 g.
900 g of dough at 75%, 20% starter, 2% salt. Total flour 900 ÷ 1.77 = 508.47 g; water to add 508.47 × (0.75 − 0.10) = 330.51 g.
1,000 g flour, 65%, 30% starter at 50% hydration, 2.2% salt. Starter 300 g holds 300 ÷ 1.5 = 200 g flour and 100 g water. Add 800 g flour and 650 − 100 = 550 g water; salt 22 g.
Other questions people ask
What is hydration in sourdough?
The weight of all the water divided by the weight of all the flour, as a percent. 350 g of water to 500 g of flour is 70% hydration. Higher hydration gives a wetter, more open dough.
Does the starter count toward hydration?
Yes, on this page. A starter is flour and water, so its flour is part of the total flour and its water part of the total water. 100 g of starter at 100% hydration adds 50 g of each, so a 500 g flour, 70% dough needs only 450 g more flour and 300 g more water.
What are baker's percentages?
Each ingredient as a percent of the total flour, which is always 100%. A 500 g flour dough at 70% water, 20% starter and 2% salt has 350 g water, 100 g starter and 10 g salt.
How much starter should I use?
Recipes often use 10% to 30% of the flour weight. More starter rises faster; less gives more time to ferment. The page takes any value from 0% to 100%.
How do I get a dough of a set weight?
Choose dough weight. The total flour is the dough weight divided by 1 + hydration + salt: 900 g at 75% hydration and 2% salt needs 900 ÷ 1.77 = 508 g of total flour.
What if my starter is stiff?
Open More options and set the starter hydration. A 50% starter has twice as much flour as water: 300 g of it holds 200 g of flour and 100 g of water.