Your sourdough starter is alive.
Boulie is the sourdough starter tracker that gives your jar a face, a mood and a voice — scan it, and AI tells you the moment it's ready to bake.
He has feelings.
They're driven by real data.
Feedings, rise, temperature, time — everything you log becomes his mood. Hungry means feed me. Peaked means bake now. You'll just know.
Point your camera at the jar.
That's it.
Scan the jar
Snap a photo. Boulie's AI reads the rise percentage straight from the glass — no rubber bands, no marker lines.
AI reads the rise
Rise %, time-to-peak and doubling speed, tracked over every feed. Your starter's rhythm, learned.
Bake at the peak
The moment it peaks, you'll know — with a notification and one very excited jar.
When is a starter ready? Stop guessing.
The float test lies — high-hydration starters sink while perfectly active, tired ones float anyway. The truth is in the rise. Boulie watches your jar peak, learns how your starter behaves at your kitchen's temperature, and tells you the moment to bake. Peak fermentation, every time.
Hydration calculator, recipe scaler,
feed reminders — built in.
Hydration calculator
Any ratio, any flour, any batch. Baker's math without the math.
Smart feed reminders
Tuned to your starter's actual rhythm and your kitchen's temperature — fridge mode included.
Bake journal
Photos, crumb shots, notes and ratings. Every loaf remembered, every bake better.
Free sourdough calculators
Use them right here in your browser. No app, no sign-up.
Sourdough Hydration Calculator
Find your dough's true hydration with the starter's flour and water counted in, plus baker's percentages and a reverse mode for target hydration.
Open calculator →Sourdough Starter Feeding Calculator
Grams of starter, flour and water for any feeding ratio, plus an estimated time to peak at your kitchen temperature.
Open calculator →Levain Build Calculator
Build exactly the levain your recipe needs: starter, flour and water in grams from the levain weight or percentage, with a buffer.
Open calculator →Bulk Fermentation Calculator
Estimate how long bulk fermentation will take from your dough temperature and starter percentage, and how much rise to aim for.
Open calculator →Baker's Percentage Recipe Scaler
Convert any bread recipe to baker's percentages and scale it to more loaves, a target dough weight or a simple multiplier.
Open calculator →Bulk fermentation chart: sourdough times by temperature
Bulk, final proof and starter peak from 60–90°F, with a stretch-and-fold schedule. Printable.
See the chart →More than bread.
Pancakes, pizza, focaccia, starter birthdays — Boulie celebrates every bake, not just the boules.
Sourdough starter FAQ
When is my sourdough starter ready to bake with?
At its peak: roughly doubled, domed and full of bubbles — before it starts to fall. Boulie reads the rise from a photo of your jar and pings you at the peak, so you bake at maximum power instead of guessing.
Do I really need the float test?
No — it's famously unreliable. High-hydration starters can fail it while perfectly ready, and over-ripe starters can pass. Rise-tracking in the jar is more accurate, which is exactly what the scan does.
How often should I feed my starter?
Room temperature: usually every 12–24 hours. Fridge: about weekly. Boulie learns your starter's actual pace and reminds you at the right time — and never guilts you when life happens.
What hydration should my starter be?
100% hydration (equal flour and water by weight) is the happy default. The built-in hydration calculator handles any ratio and scales any recipe to your batch.
What if I forget to feed him?
Starters are tough — weeks-of-neglect tough. Boulie might get dramatic about it, but one good feeding and he's back to his bubbly self. Guilt-free, always recoverable.
From the blog
Cold Proof Sourdough: How Long, What Temperature and Why
How long to cold proof sourdough in the fridge, the best fridge temperature, when to start the cold retard, and how to bake straight from the fridge.
The Sourdough Float Test: How to Do It and Why It Fails
How to do the sourdough starter float test, what floating or sinking really means, why it gives false results, and four better ways to check your starter.
Over-Proofed Sourdough: Signs, Causes and How to Save It
How to tell over-proofed from under-proofed sourdough, what the poke test really shows, why it happens, and how to rescue dough that went too far.
Name yours.
Keep him alive.
Bake at the peak.
Available now on iPhone. Scan your jar, learn your starter's rhythm, and never miss the peak again.