Yeast Conversion Calculator (Fresh, Active Dry, Instant)

Convert between fresh compressed yeast, active dry yeast and instant yeast by weight or by the spoon, in both directions, using the makers’ own published equivalences and the 2.4 to 2.7 spread between them — with what else changes: proofing, granule size and shelf life.

One ratio, and a one-for-one

The published equivalences, turned into a ratio

What changes besides the quantity

Fresh, active dry and instant: the ratio and everything else

Fresh yeast is mostly water. That is the whole reason a conversion is needed: the same number of living cells comes in a wet block, a coarse dried granule or a fine milled one, and the weights are quite different. The makers’ own charts put fresh yeast at about 2.7 times the weight of a dry yeast. Red Star publish 21 g of dry yeast as the equivalent of a 2 oz cake, which is 56.7 g, and Fleischmann’s publish the same 2 oz cake as three quarter-ounce packets — 2.667, the same answer by a different arithmetic. Their smaller retail cake gives 2.4, so the honest figure is a range, and the input above lets you set it.

Active dry and instant are one for one. This is where most conversion charts add a factor the manufacturers do not. King Arthur Baking say plainly: substitute instant yeast 1:1 by weight or volume for any active dry yeast a recipe calls for. Red Star say either active dry or instant may replace cake yeast, without distinguishing them. So this page applies no factor between the two dry forms, and says so rather than inventing one. What does change is the granule: instant is milled finer, so it has more surface area, hydrates faster and can be stirred straight into the flour. King Arthur suggest allowing 15 to 20 minutes longer for a rise if you use active dry where the recipe assumed instant.

Proofing, and what it is actually for. Active dry yeast was traditionally rehydrated in warm liquid before use, and Lesaffre’s technical data sheet for Red Star Active Dry still specifies it: at least 3.5 to 4 times the yeast’s weight in water at 38 to 43 °C. King Arthur’s position is that modern active dry no longer requires it. Both are defensible, and the secondary figures above give the water at 3.75 times the weight if you want to do it. The other reason to proof is diagnostic: Fleischmann’s describe stirring a packet into a quarter cup of warm water with a teaspoon of sugar and waiting ten minutes, and if it does not foam the yeast is dead. That is worth ten minutes before you commit 500 g of flour to it.

Fresh yeast has a much shorter life. Lesaffre give their block yeast 49 days unopened below 7 °C for optimum performance, against 24 months for the active dry. In practice fresh yeast is a few weeks in a fridge and a few days once it is opened, and old fresh yeast fails quietly — it still crumbles and smells right and simply does not lift the dough. Dry yeast in a sealed sachet is far more forgiving, which is why most home bakers use it.

By the spoon, and where this page stops. Fleischmann’s state that one quarter-ounce packet is about 2¼ teaspoons, and a quarter ounce is 7.087 g, which makes dry yeast 3.150 g per level teaspoon. That covers both dry forms. For fresh yeast there is no spoon measure and this page will not manufacture one: it is a moist crumbly solid whose spoonful depends on how hard you pressed, no maker publishes a figure, and inventing a plausible one would be the wrong kind of helpful. Choosing the spoon mode with fresh yeast gives no answer, deliberately. Weigh it.

One last thing the arithmetic will not tell you: yeast does not scale linearly with a recipe, because a larger dough holds more of its own fermentation heat and ferments faster. If you are also changing the size of the batch, read the caveats on the recipe scaling calculator. For the flour that goes with it, the cups to grams converter covers bread flour, and the oven temperature converter covers the hot oven a loaf wants.

Frequently asked questions

Related calculators

References

1. Lesaffre / Red Star Yeast. Yeast Conversion Chart (redstaryeast.com): 1 package (¼ oz, 7 g, 2¼ tsp) of dry yeast per 0 to 4 cups of flour equals ⅔ oz of fresh cake yeast, and 3 packages (21 g) equal one 2 oz cake. Also its note that either active dry or instant yeast may be substituted for cake yeast.
2. ACH Food Companies / Fleischmann’s Yeast. Frequently asked questions: one ¼-ounce packet contains about 2¼ teaspoons; one 0.6 oz cake equals one packet of dry yeast and one 2 oz cake equals three packets; and the proofing test (1 tsp sugar in ¼ cup water at 100 to 110 °F, foaming to the ½-cup mark in 10 minutes).
3. Lesaffre Yeast Corporation. Red Star Active Dry Yeast, technical data sheet (document 10415700): “Yeast should be rehydrated with a minimum of 3.5 to 4.0 times its weight in water at 38–43 °C (100–110 °F)”, and a shelf life of 24 months stored below 80 °F. The 49-day figure for block yeast below 45 °F is from Lesaffre’s own Red Star Block Yeast product page.
4. King Arthur Baking Company. Active dry vs. instant yeast: why we prefer instant (15 August 2022): “Substitute instant yeast 1:1 by weight or volume for any active dry yeast called for in your recipe”; that modern active dry no longer needs dissolving first; and that active dry may want 15 to 20 minutes more for a rise because of its larger granule size.
5. National Institute of Standards and Technology. NIST Handbook 44 (2026 edition), Appendix C, General Tables of Units of Measurement. The US liquid gallon is 231 cubic inches exactly and the British imperial gallon is 4.546 09 L exactly; every volume on this page is derived from those two definitions and the exact inch.