Yeast Converter

How the conversion works

Fresh yeast is mostly water. Dry yeast has had the water removed, so less of it does the same work. The King Arthur Baking professional reference gives two multipliers, both starting from the weight of fresh yeast:

active dry yeast = fresh yeast x 0.4

instant yeast = fresh yeast x 0.33

To go from dry back to fresh, divide by the same number. To go between the two dry yeasts, the calculator passes through fresh: it works out how much fresh yeast your amount stands for, then converts that to the type you have.

The conversion is by weight. Grams in gives grams out, and ounces in gives ounces out.

Worked example

A European bread recipe calls for 20 grams of fresh yeast.

• Active dry: 20 x 0.4 = 8 grams
• Instant: 20 x 0.33 = 6.6 grams

An American recipe calls for one packet of active dry yeast, which is 7 grams, and you have a block of fresh yeast.

• Fresh: 7 / 0.4 = 17.5 grams

You have instant yeast instead of that packet of active dry.

• 7 / 0.4 x 0.33 = 5.8 grams of instant

The three kinds of yeast

Fresh yeast, also called cake or compressed yeast, is a soft, crumbly block sold from the fridge. It is the standard in many European recipes and in professional bakeries. It keeps for a short time and must stay cold.

Active dry yeast is the granular yeast sold in packets and jars. The reference is clear that it “must be hydrated in warm water before being incorporated into a dough”, so stir it into some of the recipe’s water and give it a few minutes first.

Instant yeast has finer granules and can go straight into the flour without being dissolved. The reference adds one caution: it is sensitive to ice-cold temperatures. If your dough water is very cold, mix the dough for a minute or two before adding the yeast.

Packets, cakes and teaspoons

Recipes do not always give yeast by weight. These equivalents come from the Nebraska Extension substitution list:

• 1 packet of active dry yeast = 1/4 ounce = 2 1/4 teaspoons
• 1 cake of compressed yeast (2/3 ounce) = 1 packet of active dry yeast

The two sources agree with each other. A 2/3 ounce cake times 0.4 is 0.27 ounce, almost exactly the 1/4 ounce in a packet.

A packet is about 7 grams. If a recipe says “one packet” or “one envelope”, enter 7 grams of active dry yeast.

Adjusting the water

Because fresh yeast contains water and dry yeast does not, switching between them changes the dough’s water slightly. The King Arthur reference notes that most manufacturers suggest making up the weight difference with extra water.

In the example above, 20 grams of fresh yeast became 8 grams of active dry. The difference is 12 grams, so add about 12 grams of water, a scant tablespoon. For a single home loaf this is small enough that many bakers ignore it. For large batches it is worth doing.

Conversions are a starting point

Yeast is alive, and brands differ. A conversion gets you the right order of size. How fast the dough rises depends on its temperature, how fresh the yeast is, and how much sugar and salt are in the recipe.

Watch the dough, not the clock. If a recipe says “let rise for one hour, until doubled”, doubled is the instruction that matters. A dough made with converted yeast may take a little more or less time to get there.

Tips and common mistakes

Weigh small amounts carefully. Six grams and eight grams of yeast look the same in a bowl. A scale that reads to one gram is enough for home baking, and a pocket scale that reads to a tenth of a gram is better for small batches.

Do not pour hot water on yeast. Warm water wakes active dry yeast up. Hot water kills it. If the water feels hot to your finger, let it cool.

Check the date. Dry yeast loses strength with age, especially once the packet or jar is open. Old yeast will not be rescued by using more of it.

Keep opened yeast cold. Store an opened jar of dry yeast in the fridge or freezer, tightly closed, and keep fresh yeast in the fridge.