Baker's Yeast Conversion Calculator

The Baker's Yeast Conversion Calculator swaps fresh, active dry and instant yeast in either direction — and then does the thing a printed conversion chart cannot: it anchors the answer to your flour weight, tells you whether the dose is sensible, and predicts how long the dough will take to rise at your kitchen temperature.

Where the 3 : 1.25 : 1 Ratio Actually Comes From

Most charts simply assert that fresh yeast is three times instant yeast. That is true, but it is worth knowing why, because the reasoning tells you what else changes when you substitute. Only two properties differ between the three products: how much water they contain, and how many cells survived the drying.

Divide those activities into one another and the familiar chart falls straight out: 0.950 ÷ 0.317 = 3.0 and 0.950 ÷ 0.760 = 1.25. Fresh yeast is mostly water, which is why you need three times as much of it. Active dry is nearly as dry as instant, but the harsher drying leaves a shell of dead cells on every granule — so you weigh out about a quarter more of it. That dead-cell layer is also why active dry has to be rehydrated first: as the cells break down they release glutathione, a reducing agent that slackens gluten if it goes straight into the flour.

Yeast Conversion Chart

The three columns in each row are interchangeable. Amounts are by weight, and the spoon measures assume level, not heaped, spoons.

The Number That Really Matters: Baker's Percentage

A weight of yeast on its own is meaningless. Seven grams of instant yeast is a gentle dose in a kilogram of flour and a very aggressive one in 250 g. Bakers therefore express yeast as a percentage of the flour weight, exactly as they do for water and salt.

Why Sugar Changes the Answer

Sugar is food for yeast, but only in small amounts. Past roughly 5% of the flour weight it starts working against the yeast instead: dissolved sugar raises the osmotic pressure of the dough and pulls water back out of the cells, which slows them down. That is the whole reason osmotolerant yeast — sold as "gold" or "sweet" instant yeast — exists.

In a lean dough the two instant yeasts are interchangeable gram for gram, so there is no reason to hunt for gold yeast unless you bake sweet dough. Once sugar passes about 10%, gold yeast lets you use noticeably less product for the same rise.

Handling Each Type Correctly

How to Use This Calculator

1. Pick the yeast you have: Choose fresh, active dry, instant, gold osmotolerant yeast, or a ripe sourdough starter as your starting point.
2. Enter the amount: Type the amount and choose the unit — grams, ounces, teaspoons, tablespoons, 7 g packets or 42 g fresh cubes all work, and the spoon weights adjust to the product you picked.
3. Describe the dough: Add the flour weight, the dough temperature and the sugar and salt percentages so the tool can judge the dose and estimate the rise.
4. Click Convert Yeast: Read the equivalent weight of every yeast type, in grams, ounces, spoons, packets and cubes.
5. Or plan a dose instead: Switch to the planner, say how long you want the first rise to take, and the tool works backwards to the exact amount of each yeast.

Frequently Asked Questions

How do I convert fresh yeast to instant yeast?

Divide the fresh yeast weight by three. Fresh yeast is roughly 68 percent water and instant yeast only about 5 percent, so a gram of instant contains about three times as much live yeast as a gram of fresh. That means 30 grams of fresh yeast becomes 10 grams of instant, and one 42 gram European cube becomes 14 grams, which is two standard 7 gram packets.

What is the ratio between fresh, active dry and instant yeast?

The working ratio is 3 to 1.25 to 1 by weight. For every 3 grams of fresh yeast you need 1.25 grams of active dry or 1 gram of instant. The gap between the two dried yeasts exists because active dry is dried more harshly and loses a layer of dead cells, so you have to weigh out about 25 percent more of it than instant to get the same lift.

How many teaspoons are in a 7 g packet of yeast?

A standard packet holds 7 grams, which is 2 and a quarter teaspoons of either active dry or instant yeast. That is the same as a quarter ounce. One packet is the amount most recipes for a single loaf using 500 grams of flour call for, which works out at about 1.4 percent yeast on flour weight.

Do I need to change the rising time when I swap yeast types?

Not if you convert by weight correctly, because the converted amounts are matched on live yeast content rather than on volume. What does change is the handling. Active dry must be rehydrated in warm water at about 40 to 43 degrees Celsius for ten minutes before it meets the flour, fresh yeast is crumbled into the liquid, and instant yeast is stirred straight into the dry ingredients.

How much yeast should I use per kilogram of flour?

Between 0.8 and 1.6 percent of the flour weight is the standard range for a same-day straight dough, so 8 to 16 grams of instant yeast per kilogram of flour. Drop to 0.2 to 0.5 percent for a long or overnight ferment, and go up towards 2 to 3 percent for a heavily enriched sweet dough where sugar and butter slow the yeast down.

What is osmotolerant or gold yeast and when do I need it?

Osmotolerant yeast is an instant yeast strain bred to keep working in sugary dough. Once sugar passes about 10 percent of the flour weight it pulls water out of ordinary yeast cells and slows them down noticeably; at 20 percent sugar an ordinary yeast is running at roughly 60 percent speed while a gold strain is still near 80 percent. In a lean dough the two are interchangeable gram for gram.

Additional Resources

• Baker's Yeast - Wikipedia
• Saccharomyces cerevisiae - Wikipedia
• Baker Percentage - Wikipedia