Converting between fresh, active dry and instant yeast

A recipe asks for 25 g of fresh yeast and all you have is a sachet of dry yeast, or the other way round. This calculator converts amounts between the three most common types of baker's yeast and, once you enter the flour weight, also tells you what percentage of yeast you are using and what kind of rise to expect.

You can enter more than one type at once (for example a little fresh and a little instant): the calculator adds them into a single equivalent.

How the calculation works

• Fresh yeast (compressed, in blocks): it contains a lot of water, so you need about 3 times the weight of instant yeast.
• Active dry yeast (granules rehydrated in lukewarm water): about 1.25 times the weight of instant yeast.
• Instant yeast (dry, mixed straight into the flour): the reference, with a factor of 1.

Each amount is turned into an instant-yeast equivalent, added up and then converted back into the other two types. The percentage on flour is the instant equivalent divided by the flour weight, times 100.

Quick conversion table

With the 3 : 1.25 : 1 ratios, rounded values:

Many packets state that a 7 g sachet replaces a 25 g block of fresh yeast, a ratio of about 3.6 rather than 3. Sources range from about 2.5 to 3.5: the difference is small compared with the effect of temperature and time, but if you follow the packet you will use a little less dry yeast.

How much yeast on the flour

Yeast doses are easiest to compare as a percentage of flour weight. Examples with instant yeast:

Less yeast does not mean worse bread: it means a longer rise, which often develops more flavour. More yeast shortens the timing, but beyond a certain dose you can taste the yeast.

The reading bands

• Below 0.2% instant: a very low dose, for long fermentations such as overnight in the fridge.
• 0.2% to 0.5%: a low dose, for slow rises over many hours.
• 0.5% to 1.5%: a standard dose for bread and pizza rising for a few hours.
• 1.5% to 2.5%: a high dose, for quick rises or doughs rich in sugar and fat.
• 2.5% and above: a very high dose, typical only of very rich sweet doughs.

Practical tips

• Dissolve active dry yeast in lukewarm (not hot) water before adding it; mix instant yeast into the flour.
• Crumble fresh yeast and dissolve it in the dough water; keep it in the fridge and use it before its date.
• Long direct contact with salt slows yeast down: add the salt after mixing the yeast with the flour.
• With little yeast, temperature matters a lot: in a cool room the timing can stretch considerably.

Limits of the calculator

The ratios are indicative and vary between brands and sources. The calculator does not apply to sourdough starter, which follows different rules, or to baking powder, which is not a yeast. Rising times depend on temperature, flour, hydration, sugar and salt: the bands only give the order of magnitude.

Frequently asked questions

How much dry yeast equals 25 g of fresh yeast?

With the 3 : 1 ratio, about 8.3 g of instant or 10.4 g of active dry yeast. Many packets state 7 g of dry yeast for 25 g of fresh, a slightly higher ratio.

How much fresh yeast replaces a 7 g sachet?

About 21 g of fresh yeast if the sachet is instant yeast, using the 3 : 1 ratio.

What is the difference between active dry and instant yeast?

Active dry yeast has larger granules and is rehydrated in lukewarm water; instant yeast is finer and goes straight into the flour. You need a little less of it.

Why do the ratios differ between sources?

They depend on the moisture of the fresh yeast, the brand and the method. Sources give about 2.5 to 3.5 grams of fresh per gram of instant.

What percentage of yeast is used in bread?

Often 0.5% to 1.5% instant yeast on flour weight for a rise of a few hours; less for long fermentations.

Can I use less yeast?

Yes: the rise takes longer, but the bread often gains flavour. Very low doses are used for long fermentations, including in the fridge.

Can I mix two types of yeast?

Yes. Enter the grams of each type: the calculator adds them into a single equivalent.

Does the calculator work for sourdough starter?

No. Sourdough follows different rules and is usually dosed at a much higher percentage; it needs its own calculation.

What about baking powder?

No: baking powder is a chemical leavener, not a yeast, and does not convert with these ratios.

Does the calculator give rising times?

Only qualitatively. Real timing depends mainly on temperature and the dough.