Yeast Converter (fresh ⇄ active dry ⇄ instant)

Understanding the yeast converter — concept and principle

Recipes call for fresh (compressed) yeast, active dry yeast or instant yeast, but you usually have only one of them in the cupboard. This converter translates an amount of one type into the equivalent amount of the other two so that the dough rises on a similar schedule.

10 g fresh ≈ 4 g active dry ≈ 3.33 g instant — the drier the yeast, the less you need.

How it is calculated

The calculator uses the common weight ratio fresh : active dry : instant = 3 : 1.2 : 1.

It first converts your amount into fresh-yeast equivalent (F):

From fresh: F = amount.
From active dry: F = amount ÷ 0.4.
From instant: F = amount × 3.

Then active dry = F × 0.4 and instant = F ÷ 3. All amounts are in grams.

The principle

All three products are the same organism, Saccharomyces cerevisiae; they differ mainly in water content and in how many cells survive drying. Fresh yeast is moist, roughly 70 % water, so a gram of it contains far fewer cells than a gram of dried yeast. Active dry yeast is dried more harshly and has a layer of inactive cells, which is why it traditionally needs a little more weight than instant yeast and benefits from rehydrating first. Instant yeast is dried gently into fine particles with high viability, so it is the most concentrated and can be mixed straight into the flour.

Worked example

Default: 10 g of fresh yeast.

Fresh-yeast equivalent F = 10 g.
Active dry = 10 × 0.4 = 4 g.
Instant = 10 ÷ 3 = 3.33 g.

So 10 g fresh ≈ 4 g active dry ≈ 3.3 g instant.

Each point is the calculator re-run with only “Amount (g)” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Amount (g)	Fresh (g)
2.5	2.5
5	5
7.5	7.5
10	10
12.5	12.5
15	15
20	20

How to read the result

The numbers give an equivalent leavening power, not an exact timetable. Weigh small amounts on a 0.1 g scale if possible, because a teaspoon of dried yeast varies with how it is packed. If your dough rises faster or slower than the recipe describes, judge by the dough (volume, feel) rather than the clock, and adjust next time by about 10–20 %.

Common mistakes

Measuring dried yeast by volume and assuming it equals the gram value.
Using old or badly stored yeast; activity drops over time, especially after opening.
Adding active dry yeast directly to a stiff, cold dough without rehydrating it.
Dissolving any yeast in very hot water, which can kill it.

Keep in mind: Ratios between brands differ, and some manufacturers recommend other factors (for example, instant and active dry used almost one-for-one). When the packet gives its own conversion, follow it.

Frequently asked questions

Can I swap instant and active dry one-for-one?

Many modern active dry yeasts work well that way, but the slightly larger active dry amount here is a safer default for older or less vigorous products.

How long does fresh yeast keep?

It is perishable and is normally kept refrigerated and used within a few weeks; check the date on the block.

Does it matter for long, cold fermentation?

Yes. The longer and colder the fermentation, the less yeast you need, so scale the converted value down as the recipe directs.

Sources: Wayne Gisslen, Professional Baking (Wiley) — yeast types and substitution. · Jeffrey Hamelman, Bread: A Baker's Book of Techniques and Recipes (Wiley).

Checked 8 Nov 2026. Typical coverage rates and standard formulas. Always check the product label and local building rules; buy 5–10% extra for waste.

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