Yeast converter
Swap fresh, instant and active dry yeast by weight — and see roughly how much sourdough starter does the same job.
| Equivalent | Weight | Teaspoons | Units |
|---|---|---|---|
| Instant yeast | 7 g | 2.26 tsp | 1 × 7 g packet |
Conversion ratios
By weight, LoafCalc uses fresh : active dry : instant = 3 : 1.25 : 1. Fresh (compressed) yeast is about 70% water, so you need three times as much as instant yeast. Active dry yeast has more dormant cells than instant, so it takes about 25% more.
| You have | Instant | Active dry | Fresh |
|---|---|---|---|
| 1 g instant yeast | 1 g | 1.25 g | 3 g |
| 7 g instant yeast | 7 g | 8.75 g | 21 g |
| 10 g instant yeast | 10 g | 12.5 g | 30 g |
| 21 g fresh yeast | 7 g | 8.75 g | 21 g |
| 42 g fresh yeast | 14 g | 17.5 g | 42 g |
| 7 g active dry yeast | 5.6 g | 7 g | 16.8 g |
Sources differ: some charts use 2 : 1 for fresh to active dry. The difference matters less than temperature — a few degrees warmer or cooler changes rise time more than a 20% change in yeast. A teaspoon of instant or active dry yeast weighs about 3 g; a US packet is 7 g (¼ oz).
Converting yeast to sourdough
A practical rule: one gram of instant yeast does roughly the work of 32 g of ripe 100%-hydration starter. So 0.6% instant yeast becomes about 19% levain. Keep the overall flour and water the same and take the starter's share out of the final dough — the recipe calculator does this with one click (Convert to sourdough) and keeps hydration identical. Read the yeast conversion guide for timing and flavor tips.
FAQ
How much instant yeast equals fresh yeast?
Use one third of the weight: 21 g fresh yeast ≈ 7 g instant yeast. For active dry yeast use about 42% of the fresh weight (8.75 g).
Can I use instant yeast instead of active dry?
Yes. Use 80% of the active dry weight (7 g active dry ≈ 5.6 g instant) and mix it straight into the flour; there is no need to proof it in water.
How much sourdough starter replaces yeast?
As a rule of thumb about 32 g of ripe 100%-hydration starter per gram of instant yeast — roughly 227 g of starter for a 7 g packet — taken out of the recipe's flour and water. Rise times will be longer.