The stevia conversion ratio depends on which stevia you have

Pure Reb-A extract: how much do I actually use?

Pure Reb-A (rebaudioside A) extract is roughly 200 to 250 times sweeter than sugar by weight. The practical ratio is about 1 teaspoon of pure extract per 1 cup of sugar, not a volume-for-volume swap. Because so little is used, it adds essentially zero bulk, moisture, or structure, so any recipe that relies on sugar's volume needs a separate bulking agent.

Stevia/erythritol blend (Truvia-style): what's the ratio?

Blended products (stevia diluted with erythritol or another bulking agent specifically so it measures like sugar) convert 1:1 by volume. That is the manufacturer's intended use case: a cup of blend replaces a cup of sugar directly. In the oven it behaves like granular erythritol, with a cooling effect and some recrystallization on cooling, rather than like the pure extract.

Liquid stevia drops: same math?

Liquid drops are also highly concentrated, similar to pure extract, and are typically measured in drops rather than cups. Most bottles print their own drops-per-teaspoon-of-sugar guidance on the label, and that number varies by brand concentration. RecipeMend's Database v0.1 does not yet carry a separately verified liquid-drop entry, so treat any liquid-stevia ratio as brand-specific until you check it against that product's own label.

What happens if I use the wrong ratio?

Using a pure-extract ratio (teaspoons) with a blend product (which expects cups) under-sweetens badly and leaves the recipe with no bulk. Using a blend ratio (cups) with pure extract massively over-sweetens and can produce a bitter, licorice-like aftertaste that's characteristic of stevia at high concentration. Always check which of the two product types is in hand before converting.

Does the aftertaste differ by form?

Pure stevia extract has a well-documented bitter, licorice-like aftertaste that grows more pronounced at higher concentrations. Blended products are milder since they're diluted, though sensitive tasters commonly still report a faint stevia note.

Why doesn't stevia have one sugar-conversion ratio?

Because 'stevia' on a label can mean three very different products: pure steviol-glycoside (Reb-A) extract, a stevia/erythritol bulking blend, or liquid stevia drops. Pure extract is 200-250x sweeter than sugar by weight and used in tiny amounts (roughly 1 teaspoon per cup of sugar), while a blend is diluted with erythritol specifically so it measures 1:1 like sugar. Using a pure-extract ratio with a blend product (or vice versa) will make a recipe far too sweet or not sweet at all.

Does pure stevia extract add bulk to a recipe like sugar does?

No. Pure stevia extract is used in such small quantities that it contributes essentially no volume, structure, or moisture to a batter. Recipes that depend on sugar's bulk (creaming with butter, structure in cakes) need a separate bulking agent — such as erythritol, allulose, or extra flour or fruit puree — when swapping in pure stevia extract.

Is stevia glycemic?

No. Steviol glycosides are non-caloric and are not metabolized as sugar, so stevia in any form has no meaningful blood-glucose impact at typical use levels.