Yeast Conversion Calculator

About This Tool

The Yeast Conversion Calculator helps bakers convert between different types of yeast used in bread and pastry recipes. Yeast type substitution is one of the most common questions in home baking, and using the wrong amount can lead to dough that rises too fast, too slow, or not at all. This tool handles conversions between active dry yeast, instant yeast (also called rapid-rise or bread machine yeast), fresh cake yeast (also called compressed yeast), and sourdough starter at 100% hydration. Enter any amount of any type and see the equivalent in all other forms instantly.

Active Dry Yeast

Active dry yeast is the most common yeast in American home baking. It comes in small granules that must be dissolved in warm water (100 to 110 degrees Fahrenheit) before adding to flour. This proofing step activates the yeast and confirms it is alive before you commit your ingredients to the dough. A standard packet contains 2.25 teaspoons (about 7 grams), which is enough to leaven 4 cups of flour. Active dry yeast has a long shelf life when stored in a cool, dry place, and it keeps for months in the refrigerator or up to a year in the freezer. It produces a slightly slower rise than instant yeast, which some bakers prefer because a longer rise develops more flavor.

Instant Yeast

Instant yeast (also sold as rapid-rise, quick-rise, or bread machine yeast) is made from a more vigorous yeast strain and is processed into finer granules. It does not need to be dissolved in water first and can be mixed directly into dry ingredients. Because of its finer grind and more active strain, you need about 20% less instant yeast than active dry yeast. If a recipe calls for 1 teaspoon of active dry yeast, use only 0.8 teaspoons of instant yeast. Instant yeast produces a faster, more vigorous rise, which is why it is the preferred type for bread machines and quick-rising recipes. SAF-Instant is the most widely recommended brand among serious home bakers.

Fresh Cake Yeast

Fresh yeast, also called compressed yeast or cake yeast, is a moist, perishable product sold in foil-wrapped blocks in the refrigerated section of some grocery stores. It has a creamy, crumbly texture and a mild, slightly sweet smell. Fresh yeast must be refrigerated and used within two weeks of purchase, which is why it is less popular with home bakers than dried yeast. However, many professional bakers prefer it because it disperses easily into dough and produces a very even, predictable rise. You need about 2.5 times the weight of active dry yeast when substituting fresh yeast: if a recipe calls for 7 grams of active dry, use about 17.5 grams of fresh yeast. Crumble it directly into the flour or dissolve it in a small amount of the recipe's liquid.

Sourdough Starter Substitution

Replacing commercial yeast with sourdough starter is not a direct substitution because starter contains both yeast and bacteria, plus a significant amount of flour and water that become part of your recipe. A 100% hydration starter (equal parts flour and water by weight) is roughly half flour and half water. The general guideline is to use about 14.5 grams of active starter for every gram of active dry yeast, but this varies based on how active your starter is. You will also need to subtract some flour and water from your recipe to account for the flour and water in the starter. Sourdough fermentation is much slower than commercial yeast, so expect rise times of 4 to 12 hours at room temperature rather than 1 to 2 hours. The tradeoff is a more complex, tangy flavor and improved shelf life.

Storage and Shelf Life

Active dry and instant yeast can be stored in the pantry until the expiration date if unopened. Once opened, transfer to an airtight container and refrigerate for up to 4 months or freeze for up to a year. Fresh cake yeast must be refrigerated and used within 2 weeks. To test if dried yeast is still alive, dissolve a teaspoon in 1/4 cup of warm water with a pinch of sugar. If it foams within 10 minutes, it is active. Sourdough starter is alive and requires regular feeding (equal parts flour and water, at least once a week if refrigerated, or once or twice daily at room temperature) to remain active and viable.