Yeast Converter — Fresh, Dry & Instant

Fresh yeast	Active dry	Instant
5 g	1.75 g	1.55 g
10 g	3.50 g	3.10 g
15 g	5.25 g	4.65 g
20 g	7.00 g	6.20 g
25 g	8.75 g	7.75 g

Why are the amounts different for each yeast type?

Fresh yeast contains about 70% water by weight. Active dry yeast has been dried down to about 8% moisture, removing most of that water. Instant yeast is dried even further and milled to smaller granules, giving it a higher concentration of active yeast cells per gram.

The result: you need less instant yeast than active dry, and much less of either than fresh yeast, to leaven the same dough. The conversions in this calculator (1g fresh = 0.35g active dry = 0.31g instant) are widely used in professional bakeries.

Which yeast type should you use?

Instant yeast (also called rapid-rise or bread machine yeast) is the most convenient. Mix it directly into dry ingredients, no proofing needed. Best for same-day baking. SAF-Instant is a popular professional brand.
Active dry yeast should be dissolved in warm water (35–38 °C) with a pinch of sugar for 5–10 minutes before adding to the dough. This 'proofing' step also lets you verify the yeast is still alive.
Fresh yeast (compressed yeast) is highly perishable — keep refrigerated and use within 2 weeks. Preferred by some professional bakers for its flavour profile. Common in Europe, harder to find in North America.

Yeast Types and Their Characteristics

Active dry yeast (ADY): granulated yeast that requires proofing (activation) in warm water (38–43 °C) for 5–10 minutes before use. It has lower activity per gram than instant yeast. Standard conversion: 1 g instant = 1.25 g active dry yeast.
Instant (rapid-rise) yeast: finer granules that can be added directly to dry ingredients without proofing. More active per gram than active dry yeast. Fastest rise time of the three commercial types. Conversion: 1 g instant = 3 g fresh yeast.
Fresh (compressed) yeast: highest moisture content (~70% water). Very perishable — lasts about 2 weeks refrigerated. Most active when truly fresh; preferred by many professional bakers for its flavour contribution. Conversion: 1 g instant = 3 g fresh.
Sourdough starter (wild yeast + bacteria): activity varies widely based on starter health, ambient temperature, and feeding schedule. Cannot be converted by a simple multiplier — typically 20–30% of flour weight is used as starter, adjusted to taste and rise time.
Osmotolerant yeast: a specialty variant used for high-sugar doughs such as brioche and panettone. Regular yeast is inhibited by high sugar concentrations, causing slow or failed rises in enriched doughs.

Storage, Activation, and Signs of Failure

Active dry yeast storage: sealed in a cool, dry place → up to 2 years. Once opened, refrigerate in an airtight container and use within 4 months. For longest shelf life, freeze for up to 2 years.
Instant yeast storage: similar to active dry yeast. Once opened, transfer to an airtight container and refrigerate. Use within 4 months for best results.
Fresh yeast storage: refrigerate and use within 2 weeks. Can be frozen (wrap tightly in plastic), then thawed in the fridge — expect 10–20% activity loss after freezing. Do not refreeze thawed fresh yeast.
Proofing test (is my yeast still active?): combine 1 tsp yeast, 1 tsp sugar, and ¼ cup warm water (38–43 °C). After 10 minutes: active foam = yeast is good; no foam = yeast is dead. Do not use dead yeast, the bread will not rise.
Why yeast dies: temperature above 60 °C kills yeast cells instantly. Direct contact with undissolved salt or concentrated sugar inhibits fermentation. Yeast past its best-by date loses viability — always check before baking.

Frequently Asked Questions

Can I substitute one yeast type for another?

Yes, in most recipes. Use the conversion ratio from this calculator. The main exception is recipes that rely on a specific fermentation speed — active dry is slightly slower than instant, which can affect flavour development in long-fermented breads.

How do I know if my yeast is still good?

Proof it: dissolve 1 tsp active dry yeast in ¼ cup warm water (38 °C) with ½ tsp sugar. Wait 10 minutes. If it foams and doubles in volume, it's active. If nothing happens, discard and buy fresh. Instant yeast can also be tested this way, though it's less necessary — it's typically reliable until the expiry date if stored sealed.

What is the US standard packet size for active dry yeast?

One standard US packet of active dry or instant yeast weighs 7 g (¼ oz) and equals 2¼ teaspoons. This is enough to leaven approximately 500–750 g (4–6 cups) of flour, depending on the recipe and desired rise time.

Can I substitute instant yeast for active dry yeast directly?

Not 1:1. Instant yeast is more potent because it has smaller granules and higher viable yeast content. The conversion is: instant yeast = active dry yeast × 0.75. So if a recipe calls for 7g active dry yeast, use 5.25g instant. Also, instant yeast can be added directly to dry ingredients without proofing in water first.

Why does fresh yeast require refrigeration?

Fresh yeast contains live yeast cells in a moist cake form with no drying or inactivation. Without refrigeration, the yeast cells continue metabolizing and consuming sugars, reducing leavening power and shelf life. Fresh yeast lasts 1–2 weeks refrigerated and can be frozen for 3 months. Dry yeasts have been dehydrated to dormancy, giving them shelf stability of 1–2 years.

Can I substitute instant yeast for active dry yeast?

Yes. Use 75–80% the amount of instant yeast when substituting for active dry yeast (e.g., if the recipe calls for 10 g active dry yeast, use 7–8 g instant yeast). Instant yeast does not require proofing — add it directly to the flour. Rise times may be slightly shorter with instant yeast.

Why does my bread not rise even with fresh yeast?

The most common causes are: (1) water temperature too high — above 46 °C kills yeast; use 38–43 °C; (2) yeast in direct contact with undissolved salt — salt inhibits yeast; mix salt into flour before adding yeast; (3) yeast past its expiry date — do a proofing test to verify; (4) dough too cold — fermentation slows significantly below 24 °C; proof in a warmer location.