Sourdough Ratio Calculator
The Sourdough Ratio Calculator computes precise ingredient amounts for sourdough bread based on your desired dough weight and hydration. Calculate starter percentage, pre-fermented flour, and adjust ratios for different sourdough styles — from tangy San Francisco to mild country loaves.
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What is a Sourdough Ratio?
Sourdough ratios express the proportion of sourdough starter relative to total flour, typically 15-30% of flour weight. A common ratio is 20% starter, 70% hydration, and 2% salt. The starter's own flour and water content must be factored into the total dough formula to maintain accurate hydration.
Sourdough starter itself has a ratio — typically 1:1:1 (equal parts starter, flour, water by weight at each feeding) or 1:5:5 for less frequent feedings. The starter ratio affects fermentation speed, flavor profile (acidity), and rise quality.
使用される計算公式・方程式
この計算ツールは5つの主要な公式を使用しています：
1 Starter Amount ▼
For 20% starter with 500g flour: Starter = 500 × 0.20 = 100g.
2 Adjusted Water (accounting for starter) ▼
Assuming 100% hydration starter: half is flour, half water. Subtract the starter's water contribution.
3 Total Dough Weight ▼
500g flour + 350g water + 100g starter + 10g salt = 960g total dough.
比率計算ツールの使い方
この比率計算ツールは、以下の3ステップで簡単にご利用いただけます：
数値を入力
入力欄に既知の比率の値を入力します。求めたい未知数の入力欄は空欄のままにしておきます。
モードを選択
比率モード（解く、簡素化、スケーリング）を選択します。各モードで異なる計算式が適用されます。
結果を確認
計算するボタンを押します。結果画面に答えと、視覚的な比率バー、円グラフ、詳細なステップバイステップの解決プロセスが表示されます。
実例問題と段階的な解説
本比率計算ツールを使って、以下の3つの例題をステップバイステップで解決するプロセスです：
入力 1 Standard country loaf: 500g flour, 20% starter, 72% hydration
入力 2 High-hydration sourdough: 80% hydration, 25% starter
入力 3 Starter feeding ratio: 1:5:5
よくある質問 (FAQ)
What percentage of starter should I use? ▼
Standard sourdough uses 15-25% starter relative to total flour weight. Lower percentages (10-15%) produce milder flavor with longer fermentation. Higher percentages (25-30%) give tangier flavor and faster rise.
How does starter ratio affect sourdough flavor? ▼
More starter (25%+) speeds fermentation but produces more lactic acid (mild tang). Less starter (10-15%) with a longer cold ferment develops more acetic acid (sharp vinegar tang). Temperature also affects acid balance.
What is the ideal starter feeding ratio? ▼
For daily baking: 1:1:1 (equal parts starter, flour, water). For weekly baking: 1:5:5 or 1:10:10 before refrigeration. Higher ratios dilute acidity and give the starter more food, extending its peak window.
How do I calculate pre-fermented flour? ▼
Pre-fermented flour is the flour inside your starter. With 100% hydration starter, half is flour. If you use 100g starter, 50g is pre-fermented flour. Subtract this from your total flour to get the flour you actually add to the dough.
Can I use a different hydration starter in the same recipe? ▼
Yes, but adjust water accordingly. A 75% hydration starter has different flour/water proportions than 100%. For 100g of 75% starter: flour = 57g, water = 43g. Recalculate added flour and water.