Yeast Converter

Yeast type conversion ratios:

Conversion ratios (by weight):

• Active dry to instant: multiply by 0.75
• Active dry to fresh: multiply by 3
• Instant to active dry: multiply by 1.33
• Instant to fresh: multiply by 4
• Fresh to active dry: multiply by 0.33
• Fresh to instant: multiply by 0.25

Standard packet:

• 1 packet active dry yeast = 7 g = 2.25 tsp
• 1 packet instant yeast = 7 g = 2.25 tsp

Usage notes:

• Active dry yeast needs to be dissolved in warm water first.
• Instant yeast can be mixed directly into dry ingredients.
• Fresh yeast (cake yeast) is perishable and kept refrigerated.

The conversion ratios exist because the three forms hold different amounts of live yeast and water. Fresh (cake) yeast is mostly moisture, so it takes about three times the weight of active dry to match. Instant yeast is milled finer and more concentrated than active dry, which is why you use a little less of it.

In practice the choice affects method, not just amount. Active dry was traditionally dissolved in warm water first to wake it up, though modern strains often tolerate being mixed straight in. Instant yeast is built to go directly into the dry ingredients with no proofing, which is why it’s also sold as “rapid-rise” or “bread machine” yeast. Fresh yeast gives many bakers the liveliest rise and best flavor, but it spoils within weeks and must stay refrigerated, so most home bakers stick with the dry forms. When swapping, convert by weight rather than spoons, since the three pack very differently.

How much yeast a dough actually wants

Bakers work in percentages of the flour weight, which is the only figure that transfers between recipes of different sizes. For instant yeast:

Multiply by 1.33 for active dry, or by 4 for fresh.

Two things surprise people here. The first is how little you need: a great many recipes call for a full 7 g packet in 500 g of flour, which is 1.4% and roughly double what a decent loaf wants. Less yeast and a longer rise is the single easiest improvement most home bakers can make, because flavour develops during fermentation and a fast rise skips it.

The second is that enriched doughs need more, not less. Sugar, butter and eggs all slow yeast down, which is why a brioche recipe looks so heavily yeasted next to a lean loaf.

Temperature matters more than quantity

Yeast activity roughly doubles for every 10°C the dough warms, up to about 35°C. Past 40°C it starts dying, and 55°C kills it outright. A dough at 20°C takes something like twice as long to rise as the same dough at 27°C, so a cold kitchen in winter is usually the reason a loaf that always worked suddenly does not.

The corollary for the water: if you are proofing active dry yeast, aim for about 40°C, which feels warm but not hot on the wrist. Water straight from a hot tap is often 55°C or above and will kill it before it starts.

Storage

An unopened packet keeps for two years at room temperature. Once open, dry yeast belongs in an airtight jar in the freezer, where it stays good for a year or more; in a cupboard it fades within a few months. Freezing does not harm dry yeast, and there is no need to thaw it before use.

Fresh yeast is the exception at every point. It lasts about two weeks refrigerated, does not freeze well, and should be crumbly and cream-coloured. Brown, sticky or sour-smelling means throw it out.