How to Read a Pu-erh Wrapper: Recipe Numbers, Neifei, and Neipiao

A pu-erh cake usually comes with more than just an outer wrapper — there's a small paper embedded in the tea itself, often a separate slip tucked inside the wrapping, and frequently a number printed somewhere that looks like a product code. Each piece has a specific name and a specific job.

Neifei (内飞) — pressed into the cake, not just printed on it

The neifei ("inner flap") is a small square of paper — traditionally rice paper — pressed directly into the face of the cake during the compression itself, not glued or stamped on afterward. That's the point of it: because it's fused into the leaf while the cake is being pressed, it can't be added or swapped after the fact, which is exactly why it developed as an anti-counterfeiting mark. Chinese sources trace the practice back to pre-1950s "antique tea" (古董茶) production, when cakes had no outer wrapper at all and the neifei — naming the producer — was effectively the only identifying mark a cake carried.

Neipiao (内票), also called dàpiào (大票) — the loose info slip

The neipiao is a separate piece of paper tucked between the cake and its outer wrapper during packaging — not pressed in, just placed inside. Historically it carried factual production details: the recipe/batch number, factory name, batch, and weight. Modern neipiao are less standardized — depending on the producer, you might find a short story about the tea's origin, brewing notes, or just a greeting from the maker, rather than a strict data sheet the way older ones were.

The four-digit recipe number

Numbers like 7542 or 8582 that show up on wrappers refer to a recipe, not a specific cake. The standard convention: the first two digits are the year the recipe was originally developed, the third digit is a leaf-grade code (0 = smallest leaf grade used, 9 = largest — a size scale, not a quality ranking), and the last digit identifies the factory (2 traditionally denotes Menghai Tea Factory). Under that reading, 7542 breaks down as: developed 1975, grade-4 leaf, Menghai factory.

The catch: a recipe number identifies the formula, not the year a specific cake in your hands was actually pressed. A 7542 cake bought today can be a 2024 pressing of a formula created in 1975 — the recipe has simply stayed in production. Some factories additionally use a separate batch number (like "901" or "902") layered on top of the recipe number to indicate the actual production year and batch sequence within it; that batch-level number is the closer thing to an actual production date, and it's genuinely common for early batches of a given year's recipe to be priced meaningfully higher than later batches of the exact same formula.

A related but separate number: mǎihào (唛号)

You may also see a five-digit number called a mǎihào (唛号), most often used for grading loose maocha rather than compressed cakes: the first two digits are the processing year, the middle two are the raw-leaf grade, and the last digit is the factory code. It follows similar logic to the four-digit recipe number, but it's a distinct convention historically tied to raw material grading rather than a specific pressed product — worth not conflating with the recipe number, even though English-language sources sometimes blur the two together.

What this actually means for buying tea

None of this — neifei, neipiao, or recipe number — substitutes for buying from a source you trust. A recipe number identifies a formula; it doesn't guarantee the specific cake in front of you was made to the same standard as the factory's original run, and non-original producers sometimes reuse a well-known number for its recognition value rather than any real connection to the original recipe. Treat the wrapper details as useful context for what you're looking at, not proof of authenticity on their own.