Before you bake your first loaf, you need an active sourdough starter. It's a live culture of wild yeast and bacteria that makes your bread rise and gives sourdough its flavor. It's also the one variable the app can't control for you. A weak or inactive starter means a failed bake regardless of how well you follow every other step. Get this right first and everything else gets easier.
The fastest path to your first great loaf: get an established starter.
If you can get starter from a friend, a local bakery, or purchase a dehydrated culture online, do that. A healthy established starter that someone else has already developed will perform reliably from day one. All you need to learn is how to maintain it.
Building your own starter from scratch is absolutely doable — and we'll show you how below — but it adds 7–14 days before your first bake and introduces more variables for a beginner to manage.
Our honest recommendation: borrow or buy an established starter, get a successful bake under your belt, and then build your own from scratch if you want to. The process will make more sense once you understand what a healthy starter looks and smells like.
Path A — Maintaining an Established Starter (Recommended)
Getting your starter home alive
If you're getting starter from a friend or bakery, bring a clean jar. You only need about 50g to get started. If you're using a dehydrated culture, follow the rehydration instructions that come with it — most take 3–5 days to become fully active.
Why we use 90g feedings
The Sourdough Sanity Full Bake Guide calls for 90g of starter for a single loaf and 180g for a double batch. Feeding your starter with 90g of flour and 90g of water — and keeping 90g of culture — means you always have 270g of active starter on hand. That's enough for a double batch with 90g left over to keep your culture going. Minimal waste, always ready to bake.
Day to day maintenance
Once your starter is established, keeping it alive is straightforward:
If you're not baking: Store your starter in the refrigerator in a loosely covered jar. Feed it once a week. Take out all but 90g, add 90g of unbleached all-purpose flour and 90g of filtered or bottled water (tap water works too), mix well, and put it back in the fridge.
If you're baking: The night before your bake, take your starter out of the refrigerator. Discard all but 90g, feed it with 90g of flour and 90g of filtered or bottled water (tap water works too), cover loosely, and leave it at room temperature overnight. By morning it should be active, bubbly, and ready to use.
The biggest mistake beginners make
Maintaining too much starter. More is not better. You only need enough to complete your bake and have enough left over to keep the culture going. The 90g system above is designed specifically for this — it balances minimal waste with always having enough on hand for a double batch. Resist the urge to keep a larger quantity. It just means more flour wasted on discard and a jar that's harder to manage.
How to know your starter is ready to bake with
Your starter is ready when it reliably doubles in volume within 4–8 hours of feeding at room temperature. It should smell tangy and yeasty — like beer or plain yogurt, not like nail polish remover or rotting food. If you drop a small spoonful into a glass of water it should float. If it sinks, give it another feeding and check again in a few hours.
Path B — Building Your Own Starter From Scratch
Building your own starter takes about 7 days to establish and another week of daily feeding to make sure it's strong and consistent before your first bake. Plan for two weeks from day one to your first loaf.
What you need
- Glass jar with a loose-fitting lid
- Digital kitchen scale
- Unbleached all-purpose flour
- Whole grain flour — rye or whole wheat
- Filtered or bottled water is ideal — chlorine in tap water can slow fermentation. That said, if tap water is all you have, use it. Most municipal tap water works fine. If you're having trouble getting your starter active and you're using tap water, switching to filtered or bottled is an easy variable to eliminate. Water temperature around 75–80°F.
Day 1 — The initial mix
Combine 100g of whole grain flour (or a 50/50 mix of whole grain and all-purpose) with 150g of warm water in your jar. Mix thoroughly until no dry clumps remain. Cover loosely and leave at room temperature for 24 hours.
Day 2 — First feeding
Discard all but 90g of your starter. Add 90g of unbleached all-purpose flour and 90g of warm water. Mix well, cover loosely, and let it rest for 24 hours.
Days 3 through 7 — Daily maintenance
Every 24 hours, discard all but 90g of your starter. Add 90g of flour and 90g of water, mix well, and let it rest at room temperature.
What to watch for: by day 3 or 4 you should see bubbles forming and a tangy aroma developing. By day 7 it should be visibly active, roughly doubling in volume within several hours of each feeding.
Days 8 through 14 — Building strength
Keep feeding daily at room temperature for another week. This builds confidence — you'll learn what your starter looks and smells like at peak activity, what it looks like when it's hungry, and how it behaves in your specific kitchen environment. That knowledge will make you a better baker.
After two weeks of consistent activity your starter is ready. Switch to the maintenance routine in Path A from this point forward.
How to Know Your Starter is Ready — Applies to Both Paths
- The float test — drop a small spoonful into a glass of water. If it floats, it's ready. If it sinks, give it another feeding and check again in a few hours.
- The doubling test — mark the level of your starter after feeding with a rubber band or piece of tape. It should roughly double within 4–8 hours at room temperature.
- The smell test — it should smell tangy and slightly yeasty, like beer or plain yogurt. A sharp smell like acetone or nail polish remover means it's hungry — feed it and wait. A pink or orange tinge means contamination — start over.
If your starter passes all three you're ready to bake.
Ready to bake? The Sourdough Sanity Full Bake Guide walks you through every step of a complete sourdough bake with timers, push notifications, and technique videos built in. Download free on Android and iOS.