Somewhere past the supermarket shelf, vanilla extract starts coming in strengths: single-fold, double-fold, occasionally more. The words sound like marketing. They are the opposite: fold is one of the few terms in the vanilla trade with a federal definition behind it. Here is what the label means and when the stronger bottle earns its price.
What a fold is
In the United States, vanilla extract has a legal recipe. The FDA's standard of identity (21 CFR 169.175) says a gallon of vanilla extract must contain at least one "unit" of vanilla constituent in at least 35 percent alcohol, and the regulation next door (169.3) defines that unit: 13.35 ounces of vanilla beans per gallon, measured at 25 percent moisture or less. Beans wetter than that have to weigh in heavier to count as a full unit.
One unit per gallon is single-fold: the standard strength, and what nearly every bottle in a grocery store is. Two units is double-fold, and the law requires the fold number on the label once an extract reaches two or more. So "double-fold" is not a boast; it is a disclosure.
The math at kitchen scale
A gallon is 16 cups, so single-fold works out to about 0.83 ounces of beans per cup of liquid. The common home recipe, five to six whole beans per cup of vodka, lands at roughly an ounce per cup: slightly above the single-fold line. If you have followed our extract method, you have been making a touch better than commercial single-fold all along. The patience was the expensive part.
One quiet implication of the moisture clause: drier beans count for more. A pound of dry Grade B beans carries more extract-making power than a pound of plump Grade A, and the federal math agrees. That is most of the case for buying extract-grade beans in the first place; our grade guide makes the rest of it.
Who double-fold is for
Professional kitchens, mostly, and for reasons that have nothing to do with snobbery:
- Less liquid per unit of flavor. A bakery adding extract by the cup is also adding water and alcohol by the cup. Double-fold delivers the same vanilla in half the volume, which matters in batters and creams where liquid is budgeted.
- Consistency at volume. Half the measuring, same result, batch after batch.
- Flavor that survives the oven. More concentration going in means more vanilla left after the heat takes its share.
Triple-fold and beyond exist, mostly sold to food manufacturers. At home the returns diminish fast; past double-fold you are paying for shipping alcohol you then measure in drops.
Using double-fold in recipes
Recipes assume single-fold. When a recipe says one teaspoon of vanilla extract and your bottle is double-fold, use half a teaspoon. That is the entire conversion. (Going the other way, doubling the extract in a recipe does not make it double-fold, it makes it boozier; concentration happens in the bottle, not the batter.)
Making a stronger extract at home
Two honest routes:
- More beans from the start. Ten to twelve beans per cup instead of five or six gets you to double-fold territory. It steeps slower, because the same cup of alcohol is doing twice the work; give it six months before judging.
- Re-steep. Strain a finished extract onto a fresh set of beans and wait again. Slower still, but it converts time into concentration with no extra alcohol.
Either way, the home version will not carry a legal fold number, and does not need one. The label that matters on your shelf is the start date.
The short answer
Fold is bean weight per gallon, set by federal rule: 13.35 ounces is single, twice that is double, and the number must appear on the label from two up. Buy single-fold (or make it) for a home kitchen; consider double-fold when you bake at volume and the measuring spoon is a bottleneck. If that is you, our bulk and wholesale page is where the per-pound math starts to get interesting.