How these numbers are produced

Everything on this site is computed from public data by a script that runs on a timer. No estimates, no hand-editing.

Sources

• Fee rates and mempool state — mempool.space's public API. Live figures come from its recommended-fee endpoint; the history comes from its per-block fee-rate percentiles.
• BTC price — CoinGecko's public price endpoint, used only to convert sats to USD.

What we store

A sample of the live fee market is recorded every 10 minutes and appended to a file that is never rewritten. The historical block series was seeded once from mempool.space's published 3-month window. Current holdings: 1,105 block observations spanning 92 days, and 48 live samples collected since this site started.

How the aggregates work

Each block observation carries the 10th, 25th, 50th, 75th and 90th percentile fee rate for the block. All weekday and hourly figures on this site are averages of the median (50th percentile) rate, grouped by UTC. The median is used rather than the mean because a handful of very high-fee transactions in any block would otherwise drag the average somewhere no ordinary user ever pays.

Known limits

• The seeded history arrives in roughly two-hour buckets, so the 168-cell grid averages about 6.6 observations per cell. Treat the pattern as meaningful and individual cells as noisy.
• The "cheap / normal / expensive" verdict compares a forward-looking fee estimate against the distribution of realised block median rates. The two are closely related but not the same measurement, so treat the verdict as a rough placement rather than an exact percentile.
• Everything is UTC. Convert to your own timezone before acting on it.
• Past fee levels describe past demand for block space. They are a prior, not a forecast.
• Fee estimates are mempool.space's, not ours. When the mempool empties, every tier collapses toward the 1 sat/vB relay minimum and the tiers stop being distinguishable.

Corrections

If a number here looks wrong, it is worth reporting — the whole point of the site is that the figures are reproducible from the sources above.