Starter is already inside the recipe totals
For 1,000 g total flour, 15% starter mass means 150 g starter. At 100% starter hydration, it contributes 75 g flour and 75 g water. At 65% final hydration, add 925 g fresh flour and 575 g water. Do not add the starter twice.
Inoculation is not prefermented flour percentage
15% starter mass at 100% hydration gives 7.5% prefermented flour. Changing starter hydration changes its flour share. The master table includes starter in flour/water totals; the final-mix table tells you what to add to the measured starter.
Observe starter and dough maturity
The amount is a formula input, not a prediction of proofing time. Use a complete sourdough recipe and record starter condition, feeding, dough temperature and handling. Commercial-yeast estimates are not used as an equivalent sourdough dose.
Sources and scope
- King Arthur Baking: Baker’s PercentageFlour-based ingredient percentages.
- King Arthur Baking: Sourdough baking FAQStarter behavior and flour/water feeding.
Worked calculations and planning examples are this site’s illustrations. A source’s product or recipe guidance is not a universal pizza standard.