How to Feed a 1:2:2 Sourdough Starter Ratio to Make 75g (Same-Day 6 - 8 hrs Peak)
Fast same-day levain build math to make 75g of active starter (100% Liquid) using a 1:2:2 feeding ratio.
The arithmetic of a 1:2:2 feeding is simple: 75g of culture divided by 5 parts gives 15.0g per part, so the seed is 15g, the fresh flour is 30g and the water is 30g. At 100% Liquid this balanced 6–8 hour morning levain build build ripens in 6 - 8 hrs. If you keep a 20g jar remainder, feed 95g instead: 19g seed, 38g flour, 38g water — zero discard, permanently.
- Exact 75g Build
- 15g : 30g : 30gStarter : Flour : Water (1:2:2)
- 75g + 20g Jar Reserve
- 19g : 38g : 38gBuilds 95g total (0g discard waste)
- Estimated Peak Window
- 6 - 8 hrsAt 74°F–76°F (23.5°C–24.5°C)
- Levain Hydration
- 100%Balanced 6–8 hour morning levain build
Scaling 1:2:2 Feeds Across 55g to 95g
Peak ripening estimates assume a 75°F kitchen and 23°C room; colder kitchens need roughly 3.8% more time per degree.
| Build This Much | Seed (1 Part) | Flour (2 Parts) | Water (2 Parts) | Ripening Time |
|---|---|---|---|---|
| 65g 1:2:2 levain [Baseline] | 13g seed culture | 26g flour | 26g water | peak 6 - 8 hrs |
| 95g 1:2:2 levain Trimmed Read | 19g seed culture | 38g flour | 38g water | peak 6 - 8 hrs |
| 75g 1:2:2 levain Extended Read | 15g seed culture | 30g flour | 30g water | peak 6 - 8 hrs |
| 55g 1:2:2 levain Compact Read | 11g seed culture | 22g flour | 22g water | peak 6 - 8 hrs |
| 85g 1:2:2 levain Generous Read | 17g seed culture | 34g flour | 34g water | peak 6 - 8 hrs |
On-Bench Hydration & Fermentation Adjuster
Modify base flour mass, levain inoculation, or ambient kitchen temperature below to recalculate from this 15g : 30g : 30g baseline.
Fast Same-Day Kinetics: Why a 1:2:2 Ratio Peaks in 6 - 8 hrs (75g Build)
Monod growth kinetics explain the 6 - 8 hrs window: the 1:2:2 feed drops the seed fraction to 15.0g per 5 parts, so fermentable sugar concentration sits just above the half-saturation constant for 15g of inoculum. Yeast divides fastest while sugar is plentiful, then slows as the 30g of new flour is exhausted and lactic acid accumulates.
Shaping behaviour downstream is decided here: a levain built at 1:2:2 from 15g of seed and 30g of flour carries less residual acid than a 1:1:1 feed, so the dough it is folded into keeps more elastic recoil through bulk and produces taller oven spring.
Zero-Discard Scraping Method for 75g Levain (1:2:2)
- Never Scrap the Jar Clean: Leave a deliberate 19g remnant of starter in the vessel — this is the seed for the next 1:2:2 refresh, not waste.
- Top Up with 38g Flour and 38g Water: These two additions convert your remnant into exactly 95g of 100% Liquid levain.
- Wait for the 6 - 8 hrs Peak: Confirm the dome and the escaping gas streaks before you need the levain.
- Return the Surviving 20g: Whatever levain is left after your bake goes straight back into the jar and the refrigerator, and the cycle repeats without a single discarded gram.
Common Scaling & Troubleshooting Questions (15g : 30g : 30g)
How long does a 1:2:2 feeding take to peak?
At 75°F (24°C) the culture domes in 6 - 8 hrs; a cooler room adds roughly 3.8% for every degree below that.
What is the real difference between 1:2:2 and a 1:1:1 refresh?
A 1:1:1 refresh keeps one third of the batch as seed and peaks fastest; 1:2:2 keeps one 5th, so it ripens more slowly but with far less inherited acidity.
Can I scale this 75 g build up to 150g?
Double every number: 30g starter, 60g flour, 60g water. The ratio, and therefore the 6 - 8 hrs peak, is unchanged.