Why yeast amounts aren't fixed

A recipe that says "2 grams of yeast" is only correct for the exact time and temperature it was written for. Yeast is a living organism: it works faster when it's warm and slower when it's cold, so the same dough needs less yeast on a hot summer day than in a cold kitchen in January. Fermentation time matters just as much — the longer you let dough rise, the less yeast it takes to get there.

How to use it

• Start from flour if you know how much flour you're using, or start from dough balls if you know how many pizzas you want and how big each one should be.
• Set your hydration and salt percentages, how long you want to ferment, and your room temperature.
• Add fridge time if part of the ferment happens cold — the calculator accounts for it separately, since cold fermentation is much slower.
• Pick your yeast type. Instant dry is the default because it's the easiest to find in the US, UK, Canada and Australia and needs no proofing.

A note on temperature

The model behind this calculator is a simple linear time-temperature index — it holds up well between roughly 15–30°C (60–86°F). Above 30°C (86°F) real fermentation starts accelerating in ways a linear model can't fully capture, so accuracy drops; the calculator flags this and points you to the fridge, and it stops altogether above 35°C (95°F), where results aren't reliable enough to use.

Fresh, dry, or sourdough

Every amount on this page is derived from the same fresh-yeast figure, so switching yeast type never changes the underlying fermentation math — only the conversion. If the result for your chosen yeast drops under a gram, the calculator will show you how to dilute it in water so you can still measure it accurately with a normal kitchen scale.