This yeast converter translates between the three forms of baker’s yeast — instant, active dry and fresh cake yeast — so a recipe written for one form works with whatever is in your kitchen.
Working ratios used by most manufacturers: instant : active dry : fresh = 1 : 1.25 : 3 by weight. Technique differs more than quantity: active dry wants proofing in warm water first; instant mixes straight into flour; fresh crumbles into liquid or flour and perishes within ~2 weeks refrigerated.
The 1 : 1.25 : 3 Ladder
Fresh yeast is ~70% water, so you need about 3× the weight of instant to deliver the same living cells; active dry sits between (× 1.25 vs instant). The gulf between recipes that “fail” after a swap is usually this ratio ignored — a fresh-yeast recipe converted 1:1 to instant triples the yeast and races the dough into over-proofing. Formulas in the professional dialect live on our Baker’s Percentage Calculator, where yeast appears as a percentage of flour. Part of our Food Calculators collection.
Worked Example (Verified)
- 10 g instant (defaults) = 12.5 g active dry = 30 g fresh — about 4¼ tsp active dry, or one modest cube of fresh
- The ubiquitous 7 g instant packet = 8.75 g active dry ≈ 21 g fresh — packet math for European recipes (which love the 7 g sachet and the 42 g fresh cube equally)
- A classic French recipe calling for 20 g fresh converts to just 6.7 g instant — barely 2⅓ tsp; reach for the scale, not the spoon drawer
Handling Notes per Form
- Instant: mix with flour, keep off direct salt contact in the bowl’s first moments, stores a year+ frozen.
- Active dry: proof 5–10 minutes in 105–115 °F water; foam is the pulse check — no foam, no dough (replace it).
- Fresh: the flavor favorite of many bakers; crumble and dissolve; gray, slimy or sour-smelling fresh yeast is done, whatever the date says.
- Temperature beats quantity: a cool kitchen with the right amount outperforms a warm one with the wrong amount — dough timing follows the yeast’s environment, not just its dose.
Related Tools
- Baker’s Percentage Calculator — the formula language yeast lives in
- Pizza Dough Calculator — yeast by ball count and rise time
- Food Calculators — the full collection
Frequently Asked Questions
How much instant yeast equals fresh yeast?
Divide fresh weight by 3: 30 g fresh = 10 g instant. Fresh yeast is mostly water; the dry forms concentrate the cells. Active dry sits in between — fresh ÷ 2.4 gives active dry (30 g fresh ≈ 12.5 g).
Can I substitute active dry for instant 1:1?
Approximately, in forgiving doughs — the correct ratio is 1.25 g active dry per 1 g instant, and the proofing step matters more than the 25%: bloom active dry in warm water first or it hydrates slowly and unevenly in the dough.
How many grams are in a packet of yeast?
Standard sachets (both instant and active dry) are 7 g (¼ oz) ≈ 2¼ tsp. Fresh yeast commonly comes as 42 g cubes in Europe and 17 g (0.6 oz) cakes in the US — the converter’s gram math handles all of them.
What if my dough rises too fast after converting?
You likely converted upward (fresh → dry without dividing) or your kitchen is warm. Fixes: use cold water, refrigerate the bulk ferment, or simply reduce yeast 20–30% — long, cool fermentation also builds more flavor than the fast warm kind.
Is sourdough starter convertible this way?
No — a starter is a culture at variable strength, not a standardized product. Replacing commercial yeast with levain (or vice versa) is a formula redesign (typically 15–30% levain by flour weight and a much longer timeline), not a unit conversion.
Is this yeast converter free?
Yes — free, instant, no sign-up.