Yeast Type Conversion Calculator
Recipes call for fresh, active dry or instant yeast, but you often have a different form on hand. Because each type has a different concentration of live yeast, you convert by weight. This calculator takes a fresh-yeast weight and the relative factors for active dry and instant, and returns the equivalent weight of each form. The factors are editable so you can match your brand's stated equivalence. Defaults follow common baking practice: active dry about 0.4 of fresh, instant about 0.33 of fresh.
Yeast conversion formula
active dry = fresh * active dry factor
instant = fresh * instant factor
active dry to instant ratio = instant factor / active dry factor
(reverse) fresh = active dry / active dry factor
Convert by weight using each form's factor relative to fresh yeast. The factors are editable because yeast strength varies by brand and freshness.
Worked example
- A recipe wants 30 g fresh yeast.
- Active dry = 30 times 0.4 = 12 g.
- Instant = 30 times 0.33 = 9.9 g.
- The active-dry-to-instant ratio is 0.33 / 0.4 = 0.825, so instant is about 82 percent of the active dry weight.
- Adjust the factors if your brand lists a different equivalence.
Yeast conversion: frequently asked questions
How do the three yeast types compare?
Fresh (cake) yeast holds the most moisture and the least concentrated yeast, so you use the most by weight. Active dry yeast is dehydrated and more concentrated. Instant (rapid-rise) yeast is the most concentrated, so you use the least. Conversions are by weight using the relative activity of each form.
What conversion factors does this use?
It uses common baking conversions, all editable: active dry is about 0.4 times the weight of fresh yeast, and instant is about 0.33 times the weight of fresh (roughly three quarters of the active dry amount). If your brand specifies different factors, enter them so the conversion matches the product you use.
Do I need to dissolve each type?
Traditionally, fresh and active dry yeast are dissolved or proofed in warm liquid first, while instant yeast can be mixed straight into the dry ingredients. Follow your packet instructions, since modern active dry yeast can often also be added directly. The weight conversion is independent of how you add it.
Why are these factors approximate?
Yeast strength varies by brand, freshness and storage, so published conversion factors are guidelines, not exact constants. That is why the factors here are editable: start from the defaults, then adjust to your brand's stated equivalence or to results you trust from experience.
Official sources
- USDA FoodData Central: leavening agent reference data.
- Conversion factors are editable inputs because yeast strength varies by brand; the math is a weight times factor calculation.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.