Active dry, instant, and fresh yeast are the same organism carrying different amounts of water, so they aren't interchangeable gram-for-gram — instant is the most concentrated, fresh the least. This guide gives the by-weight conversion ratios in both directions, the packet number worth memorizing (7 g ≈ 2¼ tsp of dry yeast), and why you watch the dough rather than the clock after a swap. The free Yeast Converter does the arithmetic; the fundamentals here tell you what it's doing.
You're halfway into a recipe when you notice it calls for instant yeast and all you have is active dry. Or you've inherited a European recipe written for fresh yeast, which your grocery store doesn't even carry. The instinct is to just use the same amount and hope — and that's exactly the move that gives you a dense loaf or a dough that blows past its proof.
The three common yeasts do the same job, but they are not interchangeable gram-for-gram. Swapping them correctly takes a small amount of math, and this guide walks through it — the same conversions the Yeast Converter automates.
Why the three types aren't the same
Active dry, instant, and fresh yeast are all the same organism — Saccharomyces cerevisiae. What differs is how much water is along for the ride, and that changes how much you need.
Fresh yeast (also called cake or compressed yeast) is mostly water — a moist, crumbly block. Active dry yeast has been dried down to coarse granules but still holds a bit of moisture. Instant yeast is dried further and milled finer, making it the most concentrated of the three. The more concentrated the yeast, the less of it you need to get the same rise. That's the whole reason a straight one-for-one swap doesn't work: a gram of instant has more live yeast in it than a gram of fresh.
The conversion ratios
Here are the working ratios, by weight. These are the widely-used baking standards — close enough to manufacturer guidance to rely on for everyday bread.
By weight:
- Active dry → instant: use about 75% (multiply by 0.75)
- Instant → active dry: use about 1.33× (multiply by 1.33)
- Fresh → active dry: use about 40% (multiply by 0.4)
- Fresh → instant: use about 33% (multiply by 0.33)
- Active dry → fresh: use about 2.5× (multiply by 2.5)
- Instant → fresh: use about 3× (multiply by 3)
A worked example. Say a recipe calls for 10 g of active dry yeast and you only have instant:
- 10 g × 0.75 = 7.5 g of instant
Or the reverse — a recipe wants 7 g of instant and you have fresh:
- 7 g × 3 = 21 g of fresh
A useful anchor: the packet
If your recipe speaks in packets rather than grams, here's the number to memorize: one standard packet of active dry or instant yeast is 7 grams, which is about 2¼ teaspoons. That single fact converts most home recipes, since packets are how yeast is sold in much of the world.
Teaspoons work fine for the two dry yeasts — both come out to roughly 3.1 grams per teaspoon. Fresh yeast is the exception: it's a moist solid, not a dry granule, so it's always measured by weight, never spooned. Any conversion involving fresh yeast should stay in grams or ounces. (This is why the converter only offers teaspoons and packets for the dry types and keeps fresh yeast on the scale.)
Skip the mid-recipe math — open the Yeast Converter.
Enter your amount and yeast type and get the equivalent in the other two, by weight — with teaspoon and packet equivalents for the dry yeasts, and fresh kept on the scale where it belongs. Free, no signup, runs in your browser.
Open the Yeast Converter →What the swap does to your rise
Getting the amount right is most of the battle, but there are two practical wrinkles worth knowing.
First, instant yeast tends to work faster. Because it's more concentrated and finely milled, it dissolves and activates quickly — it can be stirred straight into your dry ingredients with no rehydrating. Active dry is a little slower off the line and, especially in a cool kitchen, often does better dissolved in warm (not cold, not hot) liquid first. So when you convert from active dry to instant, don't be surprised if the dough rises a bit quicker than the recipe's timing suggests.
Second, and this is the rule that saves more loaves than any conversion ratio: watch the dough, not the clock. A recipe's rise time is an estimate made for one type of yeast at one kitchen temperature. Once you've swapped yeast types, the timing is approximate. The dough is ready when it's roughly doubled and springs back slowly when poked — not when a timer goes off. Trust what you see over what the recipe says.
When conversion isn't the answer
One honest limit: this all applies to commercial yeasts. Sourdough starter is a different thing entirely — a living culture of wild yeast and bacteria — and it doesn't convert neatly to or from packaged yeast. The ratios above won't help you turn a sourdough recipe into a quick-yeast one or vice versa; that's a recipe redesign, not a substitution. If your recipe is built around starter, work it as written rather than trying to convert it.
Let the tool do it
The math here is simple, but it's the kind of simple that's annoying to do mid-recipe with floury hands. The Yeast Converter takes your amount and yeast type and gives you the equivalent in the other two — by weight, with teaspoon and packet equivalents for the dry types — and keeps fresh yeast on the scale where it belongs. Free, no signup, runs entirely in your browser.
Learn the packet number and the active-dry-to-instant ratio by heart; let the tool handle the rest.