Data sources and limitations

Live block height and recent speed

The primary provider is the mempool.space REST API. If it fails, the app uses the Blockstream Esplora API as a backup. Tip height comes from the height endpoint; recent speed is calculated from block metadata and timestamps at two heights.

• mempool.space tip height
• Blockstream tip height

The last 2,016 blocks provide a reference pace

The recent-pace date measures the timestamp difference between the current block and the block 2,016 heights earlier, then applies that average interval to the remaining blocks. It does not predict future difficulty adjustments or hashrate changes, so it remains separate from the main countdown.

Outages and stale data

If the primary block API does not respond, the site tries its backup provider. When neither provider is available, it first shows the last successful data and then falls back to a manual estimate based on the long-run average if no stored value exists. If recent block speed is unavailable, the reference date uses the ten-minute assumption.

The interface distinguishes live, cached, stale, and manual-estimate states so visitors can identify the source and freshness of the current value.

Cycle-coordinate data

Season 1–4 lows and highs were checked on the TradingView INDEX:BTCUSD chart using daily candles in UTC and rechecked on August 10, 2026. The Season 5 value of July 1, 2026 at $57,748 was recorded on August 21 as a provisional low candidate under the same basis. TradingView documents the index's underlying data and composition in How the BTC Index is calculated.

The original observed prices remain in the data while this page rounds them to the nearest dollar. The provisional candidate may change as the cycle develops. See the cycle-analysis methodology for the selection rule and data-state definitions →

Subsidy schedule and cumulative issuance

The subsidy table and issuance chart apply the protocol's 210,000-block interval and initial 50 BTC subsidy through a shared calculation method. The four completed dates and heights are validated against the historical halving record.

Annual new issuance is a reference based on ten-minute blocks. Years after 2028 are explanatory estimates based on an approximately four-year cadence; only target block heights are fixed by the protocol rule.

Price chart data

The price-history chart uses periodically downloaded CoinGecko BTC/USD daily closes; visitor browsers do not call the CoinGecko API directly. Days with an empty close are omitted, and weekly or monthly views use the last valid close in each period.

The valid price range runs from April 28, 2013 through August 9, 2026. The first halving predates that range, so only its reference line is shown. CoinGecko's data-use policy and attribution guide were reviewed on July 28, 2026; the official logo and source link appear next to the price chart.

Dataset reuse terms (2026-09-05)

Halving schedule calculations, subsidy schedules, curated cycle coordinates, and metadata created by BtcCal may be copied and reused provided that BtcCal and the URL of this data-information page are credited. If you modify the material, disclose that it was modified, and do not imply endorsement or approval by BtcCal or an original provider.

Third-party source data, including the CoinGecko price snapshot and observations based on the TradingView BTC Index, remains subject to each provider's terms and rights. BtcCal grants no additional rights in third-party data. The data is provided as is, without warranties of accuracy, completeness, or fitness for a particular purpose.

Service and data limitations

APIs may be delayed or unavailable, and estimated times change with actual block speed. Cycle coordinates and forecast windows are reference values based on observation rules and data coverage and are not guaranteed to be accurate.

Guides that apply these data rules