Sourdough Calculator FAQ

Short answers to the questions that come up most often when people use this sourdough calculator. If you want the longer explanation, each answer points to a guide.

What does a 1:2:2 feeding mean?

It means starter : water : flour, by weight. For every part of starter you keep, you add two parts water and two parts flour. 50 g of starter at 1:2:2 takes 100 g water and 100 g flour, and finishes at 250 g. The same idea applies to 1:1:1, 1:5:5, or a custom ratio. See starter feeding ratios.

Is the first number flour or starter?

Starter. Always read the ratio as starter, then water, then flour. If you swap the first and last numbers, the feeding will be much too large or much too small.

Why is true hydration higher than water divided by flour?

Because the starter is also flour and water. Dividing only the water you add by only the flour you add leaves those amounts out. For 500 g flour, 350 g water, and 100 g starter at 100% hydration, the shortcut is 70%. The true figure is 400 g water ÷ 550 g flour, or 72.7%. The calculator reports that second number. See true sourdough hydration.

What is starter hydration, and why is the default 100%?

Starter hydration is the water in the starter as a percent of the flour in the starter. A starter regularly fed with equal weights of water and flour is at 100% hydration, so the default is 100%. A stiffer starter, fed with less water than flour, is a lower percentage. If you leave the default at 100% for a stiff starter, the tool will overstate the water in the jar.

How do I split a starter into flour and water?

For a starter of weight S at hydration H% (as a decimal h = H/100), flour in the starter is S ÷ (1 + h), and water is the rest. At 100%, a 100 g starter is 50 g flour and 50 g water. At 50%, 150 g of starter is 100 g flour and 50 g water. The hydration panel shows this split with your numbers.

Can I use ounces instead of grams?

Yes. Switch the unit toggle to ounces and enter every weight in ounces. Do not mix grams and ounces in the same calculation, and do not enter a volume measure such as a cup. The math is the same in either unit.

Do I have to feed the whole jar?

No, and you usually should not. Weigh the seed you want to feed, or the portion going into the dough, and leave a leftover for next time. Feeding everything and then guessing how much went into the bowl makes both the jar and the dough formula less accurate. See using the calculator with your starter.

The total after a feeding seems huge. Did I do something wrong?

Check the starting starter weight and the ratio. A wide ratio such as 1:5:5 multiplies a large leftover into a very large jar. If you only need 120 g of ripe starter, start with a small seed and a ratio that gets you there, rather than feeding 100 g at 1:5:5.

Does this calculator tell me when the starter is ready to mix?

No. It only does weights and percentages. Ripeness still depends on the starter, the flour, and the temperature in your kitchen. Use the tool for the arithmetic, then judge the starter the way you already do — by rise, smell, and feel.

Why doesn’t the hydration number match how sticky the dough feels?

Hydration is a ratio of water to flour, not a direct measure of stickiness. Whole-grain flours absorb more water than many white flours at the same percentage. Temperature, mixing, and other ingredients also change the feel. Use true hydration to compare formulas fairly, not as the only test of a dough.

Can I ignore the starter if I only use a little?

You can, but the percentage you write down will be slightly off. A small starter in a large dough moves the number less than a large starter in a small dough. The calculator will show you the difference if you enter the same formula once with the starter and once with the starter weight set to zero.

Does the calculator save my recipe or send it anywhere?

No. The math runs in your browser. Nothing is submitted to a server or stored on this site. See the privacy policy for how the contact form is handled.

Will this site show ads or product links?

Not at launch. If ads or Amazon product links are added later, they will be disclosed on the page and in the affiliate disclosure. The calculator itself will stay free to use.

Who publishes this site?

Auburnbusiness.com publishes the site. For a contact form and email, see Contact. For a longer walkthrough of the default example, see how to use this simple sourdough calculator.