Sourdough Starter Feed Calculator Formula
Understand the math behind the sourdough starter feed calculator. Each variable explained with a worked example.
Formulas Used
Flour to Add
flour_needed = starter_weight * feed_ratioWater to Add
water_needed = starter_weight * feed_ratioTotal After Feeding
total_after_feed = starter_weight + starter_weight * feed_ratio * 2Estimated Peak Time
peak_hours = feed_ratio <= 1 ? (75 / room_temp * 4) : (feed_ratio <= 2 ? (75 / room_temp * 6) : (feed_ratio <= 5 ? (75 / room_temp * 8) : (75 / room_temp * 12)))Variables
| Variable | Description | Default |
|---|---|---|
starter_weight | Existing Starter(grams) | 50 |
feed_ratio | Feed Ratio (Starter:Flour:Water) | 1 |
room_temp | Room Temperature(°F) | 75 |
How It Works
How to Calculate Sourdough Starter Feeding
Formula
Flour = Starter Weight x Ratio
Water = Starter Weight x Ratio
Total = Starter + Flour + Water
The feed ratio (starter : flour : water) controls how quickly the starter reaches its peak. A 1:1:1 ratio peaks in about 4 hours at 75°F. Higher ratios like 1:5:5 take longer but produce a more mellow, less acidic flavor.
Temperature Effect
Warmer environments speed fermentation. At 85°F a 1:1:1 feed may peak in 3 hours; at 65°F it may take 6 hours.
Worked Example
50 g of starter with a 1:2:2 feed ratio at 75°F.
starter_weight = 50feed_ratio = 2room_temp = 75
- 01Flour = 50 x 2 = 100 g
- 02Water = 50 x 2 = 100 g
- 03Total = 50 + 100 + 100 = 250 g
- 04Peak time = (75/75) x 6 = 6 hours
Ready to run the numbers?
Open Sourdough Starter Feed Calculator