Class Birth-Year Supply
BTC supply decomposed across all birth-year cohorts (from genesis 2009 to current year, auto-extending) - the structural age view of the entire circulating supply. Each layer represents UTXOs minted that year that have not yet been spent.
What is it?
This metric decomposes Bitcoin's total circulating supply by the calendar year in which each UTXO was mined. Eighteen cohorts emerge (Class 2009 to Class 2026); each contains only UTXOs born that year and unspent since. The sum of all eighteen layers equals total circulating supply at any date. This view provides a fine-granularity decomposition of Bitcoin's structural supply age.
How to read
The Y axis shows absolute BTC values stacked. Bottom layer = oldest cohort (Class 2009, the Satoshi era). Top layer = most recent cohort (active). A color gradient reflects layer age (older more saturated, recent lighter). A horizontally stable layer indicates a hibernating cohort; a contracting layer indicates partial spends redistributing toward younger cohorts.
Key zones
Older layers (Class 2009-2013) remain typically very stable - they include Satoshi-era coins and early adopters, considered structurally immobile. Mid layers (Class 2014-2018) show slow attrition through cycles. Recent layers (Class 2022-2026) are more dynamic - they absorb part of older cohorts' spends during redistribution phases.
What to observe
Track relative dominance between layers: a broadening of recent cohorts (top of stack) at the expense of older ones (bottom of stack) indicates a massive redistribution phase. Conversely, older cohorts that remain unchanged even at cycle peaks mark a maturation of the holder base. Comparing the decomposition at different cycle moments (low vs peak) reveals the rotation rhythm between generations.
Historical context
UTXO birth-year analysis is a natural extension of classic HODL Waves (by age bands) that groups UTXOs into fixed calendar cohorts rather than sliding bands. This fine granularity allows identifying signature cohorts (2016, 2017, 2021) whose multi-cycle behavior has become a benchmark of long-term conviction. Complete coverage since genesis (2009) ensures an exhaustive structural view.
Expert notes
The class_{year}_supply cohorts (auto-extending each January 1st) are deterministic full-node-indexed aggregates from the Bitcoin blockchain (sum of UTXOs filtered by calendar year of creation). The B11 SOP §1.2 exception (native birth-year cohorts) applies. Trinity audit tolerance 1.5% - aggregating all cohorts slightly amplifies variance versus a single mature cohort. The youngest cohort (current year) grows with each mined block; others can only decrease via partial spends.
Common mistakes to avoid
The Class 2009 layer includes Satoshi coins (~1M BTC estimated) considered permanently locked - do not interpret them as active holdings. A long-term stable layer does not mean zero activity - it can mask micro partial spends compensated by others. Annual granularity is arbitrary (a UTXO born on December 31 vs January 1 belongs to different cohorts) - interpret boundaries as an approximation.
Programmatic access
REST API
curl -sS \
'https://api.trinityinsights.io/api/v1/onchain/class-birthyear-supply/history?days=90' \
-H 'X-API-Key: $TRINITY_API_KEY'MCP server
{
"tool": "get_chart_value",
"metric_id": "class-birthyear-supply",
"timeframe": "1y"
}Required tier: performance. See the pricing grid for the tier list and the MCP documentation for multi-client configuration.
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Institutional disclaimer
Trinity Insights is an educational and analytical tool. The metric above does not constitute investment advice. Trinity Insights is not a Crypto-Asset Service Provider (CASP) registered under MiCA Regulation (EU) 2023/1114. See the full disclaimer.