Sourdough Starter Feeding Calculator

Feed your starter at the right ratio and time so it peaks when you need it. Use this calculator whether you know when you want to mix, or you know when you are feeding right now.

How to Use This Calculator

Choose whether you know mix time or feeding time.
Pick your feeding ratio.
Use the recommended flour/water and peak window output.

Frequently Asked Questions

What is the best feeding ratio for a sourdough starter?

1:2:2 is the best starting point for most home bakers. It means one part starter, two parts flour, two parts water by weight. This ratio peaks in roughly 6 to 8 hours at 72°F, which fits a typical bake schedule. Bakers who want a milder, less acidic starter use 1:5:5 or higher. Use 1:1:1 only when you need the starter ready in 3 to 5 hours, like for a same-day bake.

How long does it take for a starter to peak after feeding?

Peak time depends on three things: feeding ratio, starter strength, and room temperature. At 72°F with a 1:2:2 ratio, a healthy starter peaks in 6 to 8 hours. A 1:1:1 ratio shortens that to 4 to 6 hours. A 1:5:5 ratio extends it to 10 to 14 hours. Cool rooms (below 68°F) can add 50% or more to all these windows. The float test confirms peak readiness.

Should I weigh starter feedings or measure by volume?

Always weigh. Volume measurements are wildly inconsistent for starter because the consistency varies from thin and bubbly to thick and stretchy depending on how recently it was fed. A scoop of peaked starter can be 30% less dense than a scoop of just-fed starter. Weighing in grams is the only way to get repeatable feeding ratios and predictable peak times.

Can I use less flour and water if I only need a small amount of starter?

Yes — in fact, scaling down is the most common mistake bakers make. If a recipe calls for 100g of starter, you need only about 20g of mature starter to feed for the build, not 100g. Use this calculator to enter your target starter amount and feeding ratio, and it tells you exactly how much old starter, flour, and water to combine. This saves significant flour over time and reduces waste.

Why is my starter doubling but not strong enough to bake?

Doubling is necessary but not sufficient. A starter ready to bake should also pass the float test (a small spoonful floats in water), smell yeasty and faintly sweet rather than sharply acidic, and show visible bubbles throughout, not just on top. A starter that doubles but won't float is usually being used past its peak or being fed at a ratio too small to build full yeast activity. Try a 1:3:3 or 1:5:5 ratio and use it at peak.

What does the ratio 1:5:5 mean for starter feeding?

It means 1 part starter, 5 parts flour, 5 parts water by weight. For a target of 220g of starter, that's 20g old starter + 100g flour + 100g water. Higher-flour ratios like 1:5:5 are popular because they extend peak time to 10–14 hours — ideal for feeding before bed and mixing dough the next morning — and produce a milder, less sour starter.

How do I keep a small starter without wasting flour?

Maintain only 20–30g of starter between bakes. Feed at 1:1:1 (so 20g + 20g + 20g = 60g total) or 1:2:2 (20g + 40g + 40g = 100g). The day before you plan to bake, do one or two larger builds at your target ratio to reach the amount your recipe needs. This approach uses about 40g of flour per maintenance feed instead of 100g+.

Does the type of flour affect feeding ratio?

Yes. Whole wheat and rye flours ferment significantly faster than white flour because they carry more wild yeast and enzyme activity. If you feed with 100% rye, expect peak time to be 30–40% shorter than the same ratio with bread flour. Many bakers blend in 10–20% whole grain for liveliness while keeping white flour as the majority to slow fermentation.

What Does a Starter Feeding Ratio Mean?

When you feed your sourdough starter, the ratio describes how much starter you keep versus how much fresh flour and water you add. A 1:1:1 ratio means equal parts starter, flour, and water by weight. A 1:2:2 means you’re diluting the starter more — giving it a larger amount of food relative to its size. The ratio directly controls how quickly your starter peaks and how acidic it becomes.

A 1:1:1 ratio peaks quickly (4–6 hours at 75°F) and produces a more sour starter. A 1:5:5 peaks more slowly but produces a milder, more active starter that holds its peak longer — better for baking. This calculator converts any ratio to real gram amounts for your jar size, so you’re not doing mental math in the kitchen.

How to Know If Your Starter Is Ready to Use

Your starter is ready when it has at least doubled in size, smells yeasty and slightly sour, and passes the float test — a small spoonful dropped into water should float rather than sink. These signals together indicate peak activity: the yeast is strong and the gluten network is intact.

Timing matters. If you regularly use a 1:1:1 ratio, your starter will peak faster than if you use 1:5:5. In winter kitchens (65°F or below), any ratio will take significantly longer than at 75–80°F. Use this calculator alongside your kitchen temperature to plan when to feed so your starter peaks right when you’re ready to mix dough.

Adjusting Ratios for Different Situations

For a same-day bake: use a 1:1:1 or 1:2:2 ratio and let it peak at room temperature for 4–8 hours. For an overnight bake: use a 1:5:5 or 1:10:10 ratio before bed and it will peak by morning. If your starter has been in the fridge for a week or more, give it one or two refreshment feeds before using it in bread.

If you’re consistently getting dense bread despite what looks like an active starter, the problem is often timing rather than ratio. The starter may have peaked and started declining before you mixed the dough. Use the float test as your confirmation, not the clock.