How Much Sourdough Starter Do You Actually Need? A Practical Guide

Most beginners maintain way too much starter. They feed 100g twice a day, throw out 90% of it, and wonder why sourdough feels expensive. Here's how to size your starter to what you actually bake.

The math behind a single bake

A typical 1kg loaf needs about 100–200g of active starter. That's it. Even if you're baking twice a week, you only need 400g of mature starter per week.

You don't need to keep 400g sitting on your counter. You need a small amount of mature starter that can be built up before each bake.

A right-sized maintenance jar

For a casual home baker baking once or twice a week:

• Keep 30–40g of starter in the fridge
• Feed once a week with 30g flour and 30g water
• Two days before baking, take it out and feed twice on the counter
• The night before, build a levain at the right size

This routine costs you about 30g of flour per week to maintain — roughly $0.05.

Building a levain instead of feeding the mother

A levain is a one-time off-shoot built specifically for a bake. The night before baking:

• Take 10g of your maintenance starter
• Add 50g flour and 50g water
• Let it rise overnight at room temperature

In the morning you'll have ~110g of levain — enough for a standard loaf, with no waste.

Sizing for bigger bakes

If you regularly bake multiple loaves or large batches:

• Two loaves: build a 220g levain (20g starter + 100g flour + 100g water)
• Four loaves: build a 440g levain (40g + 200g + 200g)

Scale the levain, not the maintenance starter. The mother stays small.

When you actually need more starter

There are real cases for keeping a larger starter on the counter:

• You bake daily for a small business
• You're testing recipes constantly
• You make a lot of discard recipes (pancakes, crackers, focaccia)

For everyone else, a small fridge starter plus a built levain is cleaner, cheaper, and produces stronger leaven anyway.

How to downsize without killing your starter

If you currently maintain 200g+ and want to scale down:

1. Discard most of it — keep just 20–30g in a smaller jar
2. Feed normally (1:1:1 by weight) for a few days
3. Move to the fridge once it's predictable

Your starter doesn't care about its size. It cares about being fed proportionally to its mass. A 30g starter fed 30g flour and 30g water is just as healthy as a 300g starter fed 300g flour and 300g water.

The waste-free principle

If you're throwing away starter every day, your starter is too big. Resize it to what you actually use, build levains for bakes, and you'll never feel guilty about discard again.