Principle 01
Weight first
Start with grams and litres for repeatable batches. Where a tool offers cups or spoons, it uses stated ingredient conversion factors.
How we calculate every number on the site
The formula behind each Ferment Calculator tool, in plain words: baker's percentages, gravity and ABV, salt by weight, and where each method comes from.
Understand the numbers before you use them
Three principles behind the tools and their results.
Principle 02
Make assumptions visible
Check the formula, units and reference assumptions on the calculator page. They explain what the result means and how to check it.
Principle 03
Estimates have limits
Use results to plan your batch. Ingredients, cultures and temperature vary; a calculator cannot certify food safety or replace a tested process.
Sourdough
11 calculators · formulas, assumptions and practical guidance on each tool page.
- Pizza Dough Calculator Calculator · Scale sourdough or yeast pizza, with size presets, starter hydration and party batches.
- International Flour Type Converter Calculator · Compare German, French, Italian and US labels with approximate matches and substitution guidance.
- Sourdough Hydration Calculator Calculator · Baker's percentages: flour is 100% and everything else is a share of the flour. Flour = total dough ÷ (1 + hydration ÷ 100), and water is the rest.
- Bulk Fermentation Time Calculator Calculator · Starts from 5 hours for dough at 24°C with 20% starter, 75% hydration and a 50% rise. Time doubles for every 8°C cooler and halves for every 8°C warmer. Less starter, whole grain flour, hydration and the rise you aim for each adjust the time from there. These factors are our planning assumptions, not calibrated measurements, so the result is a window to check against the dough.
- Sourdough Starter Feeding Calculator Calculator · A feed ratio such as 1:5:5 is split into equal parts by weight: starter, flour and water each get their share of the total you want to end with.
- Sourdough Starter Manager Calculator · Log each feed, watch the expected rise against the clock, record when your starter peaked, and learn its own timing.
- Sourdough Ratio Calculator Calculator · Scale the classic 1:2:3 sourdough dough ratio (starter : water : flour) or any starter feeding ratio to exact gram weights, with overall hydration.
- Sourdough Discard Calculator Calculator · How much discard do you have? Calculate substitutions for pancakes, crackers, waffles, and more.
- Levain Calculator Calculator · The levain is a percentage of the dough flour. Its own flour = (levain weight less the seed starter) ÷ (1 + levain hydration ÷ 100). The seed is 10% of the levain, so its peak estimate uses the 1:5:5 row of our starter-timing table.
- Baker's Percentage Calculator Calculator · Turn your flour weight and ingredient percentages into exact grams for water, salt, starter, fat, and sugar — and scale any recipe.
- Bread Flour Cups to Grams Converter Calculator · Convert cups of bread flour, all-purpose, whole wheat, water, and more to grams — and back — with standard baking weights.
- Peak-time estimates: King Arthur Baking, sourdough feeding ratio comparison (2025)
- Reference for Starter feeding calculator
- Rise targets by flour protein: The Sourdough Framework, Chapter 7 (§7.9)
- Reference for Bulk fermentation time
Mead
7 calculators · formulas, assumptions and practical guidance on each tool page.
- Mead ABV Calculator Calculator · ABV = (original gravity − final gravity) × 131.25. Refractometer readings are converted to gravity first, with the alcohol correction for the final reading.
- Mead Honey Calculator Calculator · From the strength you want: starting gravity = the expected finishing gravity + ABV ÷ 131.25. Honey adds about 35 gravity points per pound per US gallon, so pounds per gallon = gravity points ÷ 35.
- Mead Recipe Calculator Calculator · Enter batch size, target ABV, sweetness, and yeast to get a full mead recipe — honey, water, OG/FG, nutrients, and yeast amounts.
- Mead Batch Calculator Calculator · Scale any mead recipe up or down. Enter your target batch size and get exact honey, water, and nutrient amounts.
- Mead Nutrient Calculator Calculator · The dose scales with the sugar in the must: grams per gallon rise with gravity points, adjusted for the nutrient you use, then split into additions up to the one-third sugar break.
- Mead Priming Sugar Calculator Calculator · Sugar = (target carbonation − carbonation already in the mead) × litres × the sugar factor: about 4.01 g/L of dextrose or 3.82 g/L of table sugar per volume of CO2.
- Mead Calories Calculator Calculator · Estimate calories per glass based on ABV, residual sugar, and serving size. Useful for tracking your homebrew intake.
Kombucha
5 calculators · formulas, assumptions and practical guidance on each tool page.
- Kombucha Brewing Calculator Calculator · Calculate tea, sugar, starter liquid, and SCOBY ratios for any batch size. First fermentation times included.
- Kombucha Sugar Calculator Calculator · How much sugar does your kombucha need? Calculate by batch volume and target sweetness level.
- Kombucha Batch Calculator Calculator · Sugar and tea scale with the batch in grams per litre. The starter liquid is a set share of the batch, and the water is the rest.
- Second Fermentation Calculator Calculator · Juice is a percentage of the bottle volume and added sugar is grams per litre, both scaled to your batch.
- Kombucha Alcohol Content Calculator Calculator · Each gram of sugar can make at most 0.51 g of alcohol, and alcohol weighs 0.789 g per millilitre. The share of sugar the culture has used is estimated from the days in the first ferment and the temperature.
Yogurt
3 calculators · formulas, assumptions and practical guidance on each tool page.
- Yogurt Starter Calculator Calculator · Starter is dosed per litre of milk, with a different rate for live yogurt, freeze-dried packets and heirloom cultures.
- Yogurt Milk Ratio Calculator Calculator · Find the right starter-to-milk ratio for thick, creamy yogurt. Adjust for different milk types and fat percentages.
- Greek Yogurt Yield Calculator Calculator · Yogurt is weighed at 1.03 kg per litre. The share kept after straining falls with straining time and depends on the milk fat; the whey is the rest.
Kefir
4 calculators · formulas, assumptions and practical guidance on each tool page.
- Kefir Calculator Calculator · Grains are grams per litre of milk or sugar water, and sugar for water kefir is grams per litre by how sweet you want it, shown in spoons and cups at a fixed weight per spoon.
- Milk Kefir Calculator Calculator · Choose a slow, standard, or fast milk-grain protocol with practical check windows and safety guidance.
- Water Kefir Calculator Calculator · Keep grains at 60 g/L and calculate light, standard, or rich sugar water for any batch size.
- Water Kefir Sugar Calculator Calculator · Scale 45, 55, or 70 g sugar per litre with measured mineral, timing, alcohol, and pressure guidance.
Cheese
4 calculators · formulas, assumptions and practical guidance on each tool page.
- Cheese Yield Calculator Calculator · Milk is weighed at 1.03 kg per litre. Cheese = milk weight × the typical yield for that cheese, adjusted for the milk. Whey is the rest, at 1.02 kg per litre.
- Rennet Calculator Calculator · Starts from 1/4 teaspoon of single-strength liquid rennet per US gallon (about 0.33 ml per litre), then scales for the rennet type and the cheese. One tablet sets 2 US gallons.
- Milk to Cheese Calculator Calculator · Reverse-calculate: how much milk do you need to make X grams of cheese? Works for cheddar, mozzarella, ricotta, and more.
- Cheese from Milk & Vinegar Calculator · How to make cheese from milk and vinegar: get the exact vinegar to add, the fresh-cheese yield to expect, and the whey left over.
Brine & Pickling
5 calculators · formulas, assumptions and practical guidance on each tool page.
- Fermentation Brine Calculator Calculator · Salt = weight before salt × salt % ÷ 100. The weight is the water, the vegetables, or both, depending on what your recipe measures. Salt is always weighed, never measured by the spoon.
- Pickling Brine Calculator Calculator · Calculate vinegar, water, and salt ratios for any pickling jar size. Works for cucumber pickles, sauerkraut, kimchi, and more.
- Salt Brine Calculator Calculator · Enter your target salt percentage and vessel volume — get the exact grams of salt to add. Works in metric and imperial.
- Pickling Ratio Calculator Calculator · Vinegar, water, and salt for any batch of pickles. Canning-safe mode holds the 1:1 acid floor; quick-pickle mode opens the ratio up to taste.
- Canning Altitude Adjustment Calculator Calculator · Adds processing minutes for a boiling-water canner by altitude band.
- National Center for Home Food Preservation
- Reference for Fermentation brine calculator
- USDA and the National Center for Home Food Preservation
- Reference for Canning altitude adjustment
Brewing
11 calculators · formulas, assumptions and practical guidance on each tool page.
- ABV Calculator (Beer, Wine & Cider) Calculator · ABV = (original gravity − final gravity) × 131.25.
- Brix to Specific Gravity & ABV Converter Calculator · Brix to gravity with the standard polynomial, and a corrected final reading for a refractometer used after fermentation has started.
- Specific Gravity & OG/FG Calculator Calculator · Enter original and final gravity to get ABV, apparent and real attenuation, gravity points, °Plato, real extract, and calories.
- Beer IBU Calculator & Chart Calculator · Bitterness from hop weight, alpha acid, boil time, wort gravity and batch size, using the Tinseth hop bitterness formula.
- Yeast Starter & Pitch Rate Calculator Calculator · Work out how much yeast to pitch from batch size, gravity, and beer type — target cell count, liquid packs, and dry yeast grams.
- Hydrometer Temperature Correction Calculator Calculator · Correct hydrometer readings for temperature — enter your measured SG, sample temperature, and calibration temp to get the true specific gravity.
- Beer Carbonation & Priming Sugar Calculator Calculator · The CO2 already in the beer is worked out from its temperature. Sugar = (target − that) × litres × the factor for your sugar: about 4.0 g/L of corn sugar or 3.8 g/L of table sugar per volume of CO2.
- Brewing Water Chemistry Calculator Calculator · Build your water profile from source minerals and brewing salts — gypsum, calcium chloride, Epsom salt, and more. See SO₄:Cl ratio and style match.
- Beer Recipe Calculator & Builder Calculator · Estimate OG, FG, ABV, and SRM from your grain bill, efficiency, and yeast attenuation. Plan recipes with 14 common grain types.
- Extract Brewing OG Calculator Calculator · Estimate original gravity and potential ABV for an extract batch from your DME, LME, steeping grains, and batch volume.
- Strike Water Calculator Calculator · Strike temperature = (0.41 ÷ litres per kg)(mash target − grain temperature) + mash target, or 0.2 with quarts per pound in °F.
Fermented Sodas
1 calculators · formulas, assumptions and practical guidance on each tool page.
Vinegar
1 calculators · formulas, assumptions and practical guidance on each tool page.
Koji, Miso & Soy
1 calculators · formulas, assumptions and practical guidance on each tool page.
