Breads & dairy Sourdough Precision baking starts here 11 calculators 44 guides Explore Sourdough Always free · No account · Answers as you type
Free fermentation calculators for every ferment
Calculators and guides for sourdough, mead, kombucha, yogurt, kefir, cheese, brine, brewing, wine and cider, sodas, vinegar, and koji, miso and soy.
- calculators
- 53
- guides
- 267
- kinds of ferment
- 12
New · Featured tool
Sourdough Starter Manager
Log each feed, watch your starter rise in a 3D jar and record when it peaks. After two feeds it learns your own starter’s timing, so you know when it will be ready.
- See the rise against the clock
- Learns your starter’s peak time
- Free, no account needed
Troubleshoot your ferment
Dense sourdough, flat kombucha, or a stalled batch? Find out what went wrong and what to do next.
- My sourdough is over-proofed Sourdough
- Why is my sourdough dense? Sourdough
- There is liquid on top of my starter Sourdough
- Is this mold on my kombucha? Kombucha
- My kombucha is not fizzy Kombucha
- How long does sauerkraut last? Brine & Pickling
- My mead stopped fermenting Mead
- How much priming sugar do I need? Brewing
Choose your fermentation
12 kinds of ferment. Each hub has calculators, step-by-step guides and printable logs.
- Breads & dairy Sourdough Precision baking starts here 11 calculators 44 guides Explore Sourdough
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Breads & dairy Yogurt Starter ratios for steadier yogurt 3 calculators 8 guides Explore Yogurt -
Breads & dairy Kefir Ratios for grains, milk, and water kefir 4 calculators 21 guides Explore Kefir - Breads & dairy Cheese Make cheese with confidence 4 calculators 38 guides Explore Cheese
- Drinks Kombucha Brew balanced kombucha every time 5 calculators 23 guides Explore Kombucha
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Drinks Mead Brew better mead with precision 7 calculators 26 guides Explore Mead -
Drinks Brewing Beer, wine & cider brewing calculators 11 calculators 32 guides Explore Brewing -
Drinks Wine & Cider Wine and cider making guides & calculators 3 calculators 2 guides Explore Wine & Cider -
Drinks Fermented Sodas Ginger bug, tepache, kvass & wild soda guides 1 calculator 7 guides Explore Fermented Sodas - Pickles & pantry Brine & Pickling Precise salt ratios for lacto-fermentation 5 calculators 31 guides Explore Brine & Pickling
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Pickles & pantry Vinegar Homemade vinegar guides & calculators 1 calculator 6 guides Explore Vinegar -
Pickles & pantry Koji, Miso & Soy Koji, miso, soy sauce, tempeh & natto guides 1 calculator 8 guides Explore Koji, Miso & Soy
Logs and books
Logs and reference books to help you plan, track and improve your ferments. Every purchase helps keep the calculators free.
Printed book · Delivered to you
The Kefir Log Book
A spiral-bound book delivered to your door, ready to write in. Milk and water kefir notes, together in a spiral-bound book.
Printed book · Delivered to you
The Sourdough Log
A spiral-bound book delivered to your door, ready to write in. 52 bake records in a spiral-bound journal that lies flat.
Digital download · Print at home
The Sourdough Log
Download the files and print your own copy. No book is shipped. 52 guided bake spreads to download and print at home.
Printed book · Delivered to you
The Kombucha Log Book
A spiral-bound book delivered to your door, ready to write in. F1 and F2 notes, together in a spiral-bound book.
Printed book · Delivered to you
The Yogurt Log
A spiral-bound book delivered to your door, ready to write in. 52 batch records in a spiral-bound journal that lies flat.
Digital download · Print at home
The Yogurt Log
Download the files and print your own copy. No book is shipped. A year of thick, tangy set.
Digital download · Print at home
The Sourdough Formula Book
Download the files and print your own copy. No book is shipped. Baker's percentages, worked out for you.
Digital download · Print at home
The Mead Maker's Book
Download the files and print your own copy. No book is shipped. The honey math, worked out for you.
Digital download · Print at home
The Kombucha Brewing Book
Download the files and print your own copy. No book is shipped. Sweet tea, timing and fizz, worked out.
Digital download · Print at home
The Dairy Ferments Book
Download the files and print your own copy. No book is shipped. Cheese, yogurt and kefir, by the numbers.
Digital download · Print at home
The Fermentation Brine Book
Download the files and print your own copy. No book is shipped. The right salt percentage, every jar.
Digital download · Print at home
The Homebrew Numbers Book
Download the files and print your own copy. No book is shipped. OG and FG to ABV without the guesswork.
Newsletter
One email a month
What I updated on the site, one ferment that suits the season and anything new in the shop. No spam; unsubscribe from any email.
Questions
Frequently asked questions
About Ferment Calculator
Are all the calculators free?
Yes. Every calculator on Ferment Calculator is free to use, with no signup. We offer optional free PDF downloads (email required) and paid printable journals in our shop.
What fermentation types do you cover?
We cover sourdough, mead, kombucha, yogurt, kefir, cheese, brine and pickling, brewing, wine and cider, fermented sodas, vinegar, and koji, miso and soy. Each category has its own hub with calculators, free guides and printable reference sheets.
How accurate are the fermentation calculators?
Our calculators use the same formulas bakers, meaderies and brewers use. Sourdough hydration uses baker's percentages, mead ABV uses the standard gravity formula, and brine uses salt by weight. Every method is written out on How we calculate.
Can I use these calculators on mobile?
Yes. Every calculator works on any phone, tablet or computer. There is no app to download.