Calculate the scaling factor
Divide the desired yield by the original yield, then multiply each ingredient by that factor. To turn four portions into six, multiply by 1.5. Use weights when possible and record units clearly; fluid ounces and ounces by weight are different measures.
Do not multiply the clock
A doubled batch may need a wider pot, extra trays or multiple batches. Increased depth changes baking and cooling. Cooking time depends on thickness, temperature and equipment, so follow doneness cues and safe temperatures rather than doubling the timer.
Read baker’s percentages
In baker’s math, total flour weight is 100%. With 500g flour and 325g water, hydration is 65%. To make the same ratio with 300g flour, use 195g water. Other ingredients are also expressed relative to flour, so the percentages add to more than 100%.
Keep experiments controlled
A recipe ratio describes a relationship; it does not guarantee a complete method. Yeast amount, flour choice, temperature and mixing affect results. Scale a known recipe before improvising, and make small trial batches when changing ingredient types.
Your next kitchen exercise
Scale a four-serving recipe to six servings. Then calculate the hydration of a bread formula using total flour and water, including any starter.
