Transaction Fee (P90) shows the 90th-percentile fee paid on a given day. Ninety percent of transactions paid this fee or less, so the series isolates the upper end of the transaction-fee distribution in satoshis per transaction.
A rising P90 means higher-fee transactions are becoming more expensive. If P90 rises while the median stays flat, the tail is stretching before the center of the market moves. It works best with Average Transaction Fee and Median Transaction Fee.
The key limitation is scope. P90 does not describe the typical transaction, and by itself it can overstate how broad fee pressure really was. Its value is in locating upper-end stress that the mean or median alone cannot place.
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