Yeast Converter

Bread recipes travel between generations, countries and shops that don't always stock the same yeast. This converter translates between fresh (cake) yeast, active dry, instant, fast-action and easy-bake yeast so a recipe your grandmother wrote for a bakery block still works when all you have is a supermarket sachet — and vice versa. Get the swap right and the dough will rise on schedule; get it wrong and you'll either wait hours for nothing to happen or watch the loaf collapse from over-proving.

It's aimed at anyone who bakes bread, brioche, pizza, buns or enriched doughs at home. Whether you've inherited a continental recipe calling for fresh yeast, bought instant yeast in bulk from a wholesaler, or ended up with a mystery sachet at the back of the cupboard, this tool gives you the equivalent weight of the yeast you actually have to hand.

How the calculation works

Every yeast type is expressed as a multiplier of fresh yeast. Fresh is 1.0 (the reference), active dry is 0.4, and instant / fast-action / easy-bake are 0.33. To convert, we first work out how much fresh yeast your original amount is equivalent to, then multiply that by the factor for the type you want to end up with.

The formula is new = (original ÷ factor of original type) × factor of new type. It's the same maths bakers use in their heads, just written out. The result is rounded to one decimal place because bread doughs are forgiving to within a fraction of a gram — but not to within whole grams.

A worked example

Your grandmother's cinnamon-bun recipe asks for 30 g of fresh yeast. You only have a jar of instant. Converting: 30 × 0.33 = 9.9 g of instant, which rounds neatly to about 10 g — or one and a half standard 7 g sachets. Add it straight to the flour, mix, and expect the same rise time as the original recipe.

Going the other way, a modern UK recipe calls for one 7 g sachet of fast-action yeast and you'd rather use fresh. 7 ÷ 0.33 = 21 g of fresh yeast. Crumble it into the warm liquid before adding to the flour.

Why this matters

Yeast is the leavening in almost every enriched dough and traditional bread. Too little and the loaf is dense and under-risen; too much and it over-proves, tears at the top and develops a yeasty aftertaste. Because the three yeast types differ in strength by up to three-fold, you can't ignore the conversion — the difference between 7 g of fresh and 7 g of instant is enormous.

Limitations to be aware of

Conversions are close but not perfect. Yeast strength varies slightly between brands and drops as the packet ages. If your dried yeast has been open for a few months, err on the higher end of the conversion or do a quick proofing test in warm sugared water to confirm it's still active. Sourdough starters are a different creature entirely and can't be substituted at these ratios.

Common mistakes

• Swapping one-for-one by weight — the single biggest reason home bread flops. Instant is roughly three times stronger than fresh.
• Using boiling water to activate yeast — anything above 50°C kills it. Warm bath temperature is the target.
• Adding salt directly onto the yeast — salt draws water out of yeast cells and damages them. Mix salt with the flour first.
• Trusting a very old packet — yeast loses vitality over months even sealed. Test in warm sugared water first if in doubt.
• Not adjusting first-rise time when swapping types — active dry needs a few extra minutes to hydrate. Instant is off to the races immediately.
• Confusing "sachet" measures across recipes — UK sachets are 7 g, some European sachets are 5 g or 11 g. Weigh rather than count.

Related tools in the Kitchen hub: Recipe Scaler · Grams to Cups · Oven Temperature · Baking Time Adjuster