Easily calculate sourdough starter feeding ratios, adjust hydration percentages, and convert starter amounts with this free baker's math tool for home bakers.
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Sourdough Starter Hydration & Baker's Math Tool
Overview
This single-file application is a specialized utility designed for sourdough bakers to manage starter feedings and hydration adjustments. It functions as a real-time calculator that removes the guesswork from baker's math.
Core Features
- Hydration Conversion Engine: Calculate exact water and flour amounts to convert a starter from one hydration level (e.g., 100%) to another (e.g., 60% or 80%).
- Feeding Ratio Calculator: Determine the weight of flour and water required based on a desired feeding ratio (e.g., 1:2:2 or 1:5:5).
- Target Yield Adjustment: Input the total weight of active starter needed for a recipe, and the tool will work backward to calculate the required ingredients.
- Real-Time Updates: As the user changes any input field, all result outputs update immediately without requiring a "Calculate" button click.
- Clear Summary Table: A cleanly formatted breakdown of the final ingredients needed.
User Interface & Design
- Aesthetic: A professional, "SaaS-light" design. Clean typography, generous whitespace, and a high-contrast, professional color palette (Soft Slate, Crisp White, and Warm Baker's Gold as an accent).
- Layout:
- Header: Minimalist title and description.
- Main Inputs: A two-column grid (desktop) or stacked (mobile) layout for "Starter Source" (Weight/Hydration) and "Target Goal" (Desired Yield/Hydration).
- Results: A dedicated card section highlighting the final amounts of flour, water, and starter to mix, displayed in large, readable typography.
- Transitions: Use CSS
transition: all 0.3s easefor input focus states and result updates. Add a subtle "pulse" animation when results update.
Technical Implementation Constraints
- Architecture: The entire app must be a single HTML file containing embedded CSS and Vanilla JavaScript.
- No Persistence: Under no circumstances should
localStorage,sessionStorage, or cookies be used. State must be handled by JavaScript variables. If the page is refreshed, the app should return to its default state. - Sandbox Safety: The application will run in an iframe. Avoid blocking browser calls like
prompt()orconfirm(). Any user interaction requiring a modal should be built using native HTML/CSS overlays. - Responsiveness: Use CSS Flexbox/Grid to ensure the tool is fully usable on mobile phones, tablets, and desktops. No horizontal scrolling should ever be required.
- Dependencies: Only standard, reliable CDNs. For example, use a modern font from Google Fonts (e.g., 'Inter') and perhaps a lightweight utility icon set (e.g., Lucide or Heroicons) via SVG/CDN.
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Frequently Asked Questions
Everything you need to know about using this application.
How do I change my sourdough starter hydration using this tool?
To change your starter's hydration, you need to adjust the ratio of water to flour in your feeding cycle. Simply input the weight of your existing starter, its current hydration percentage, and the target hydration you wish to achieve. The tool will instantly calculate the precise amounts of fresh flour and water needed to transition your starter to the new hydration level. This is particularly useful when converting a liquid starter to a stiff starter for specific bread styles or when following a new recipe that requires different moisture levels.
What is baker's math and why is it important for sourdough?
Baker's math is a system of measurement used by professional and home bakers where the total flour is always represented as 100%. All other ingredients, such as water, salt, and leaven, are calculated as a percentage of that total flour weight, ensuring that the consistency and structure of your dough remain identical regardless of the batch size. Using this methodology provides consistency across your bakes, allowing you to easily scale recipes up or down. By using a calculator for your starter, you ensure your levain or mother culture is always fed at the correct ratio to maintain peak activity and predictable fermentation times.
Does this tool save my baking data or preferences?
This application operates entirely in your browser's memory and does not use cookies, local storage, or server-side databases. Your inputs are ephemeral, meaning that once you refresh the page or close your browser tab, all calculation data is cleared immediately. This approach ensures that your usage remains private and secure. Since no data is persisted, you are provided with a clean slate every time you load the tool, which is ideal for quick, one-off calculations during your daily baking routine.
Why should I use a calculator instead of doing the math manually?
Calculating feeding ratios manually can often lead to minor arithmetic errors, especially when working with high-hydration starters or converting large batches. Even small mistakes can cause inconsistencies in your starter's fermentation activity, leading to unexpected results in your final loaf of bread. Using a dedicated tool eliminates these errors and saves time, helping you build exactly the amount of active starter you need for your specific recipe without wasting excess flour or water. It provides immediate, accurate results so you can spend less time measuring and more time baking.
