Metric guide

Definitions, calculations and limitations

Use this guide to understand what each group measures, how 21Relay transforms the values and where interpretation requires care.

Live

A recently retrieved observation.

Cached

The last successful result is shown because a fresh request did not complete.

Delayed

A valid observation that updates periodically rather than continuously.

Estimated

A recommendation, projection or inferred measurement rather than a direct protocol value.

Unavailable

No sufficiently recent successful value is available, so the metric is omitted or marked unavailable.

Metric group 01

Market price and history

Current BTC-fiat quote, historical price movement, change, range and drawdown

Update behaviour: Current quotes refresh frequently. Longer historical windows refresh less often and may use a cached result.
Calculation: Historical observations are reduced to a readable chart while retaining the start and end of the selected window. Percentage change and drawdown are calculated from those observations.
Interpret carefully: A displayed quote is informational, not an executable price. Prices can differ across trading venues, spreads and currencies.

Metric group 02

Block height, recent block pace, block fill, mempool size and queued transactions

Update behaviour: The tip and transaction-pressure view refresh about once per minute when current data is available.
Calculation: Recent pace and fill are calculated from a short block sample. Queue size is translated into an approximate number of blocks using one virtual megabyte per block.
Interpret carefully: A short block sample naturally varies around Bitcoin's ten-minute target. Individual nodes can observe slightly different mempools.

Metric group 03

Priority fee rates, fee spread and example transaction costs

Update behaviour: Fee estimates refresh with current transaction-pressure data.
Calculation: Example costs multiply the selected sat/vB rate by representative transaction virtual sizes. They are educational scenarios rather than wallet quotes.
Interpret carefully: No fee estimate guarantees confirmation in a particular block. Conditions can change after a transaction is sent.

Metric group 04

Estimated hashrate, current difficulty, adjustment progress and projected change

Update behaviour: Mining observations and adjustment projections refresh every few minutes.
Calculation: Hashrate is inferred from observed block production and difficulty. The next adjustment is a moving projection across the current 2,016-block period.
Interpret carefully: Hashrate is not directly measurable and the projected adjustment can change materially as new blocks arrive.

Metric group 05

Nominal issued supply, current subsidy, daily issuance and next halving

Update behaviour: These values recalculate whenever the latest block height changes.
Calculation: Integer satoshi arithmetic applies Bitcoin's 210,000-block subsidy schedule. Daily issuance assumes Bitcoin's long-run target of approximately 144 blocks per day.
Interpret carefully: Issued supply is a protocol calculation and does not estimate lost coins or currently spendable supply.

Metric group 06

Bitcoin performance, consumer-price change, broad-money growth and purchasing-power indexes

Update behaviour: Market history can update frequently; annual economic observations update slowly and may lag the current year.
Calculation: Series are aligned by calendar year and normalized to 100 at the first shared observation so unlike units can be compared on one scale.
Interpret carefully: National statistics can be revised. These comparisons are descriptive and do not predict future purchasing power or investment returns.

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