Average Block Size (bytes)
Daily average block size in bytes. Directly reflects on-chain data demand including inscriptions, OP_RETURN data, and transaction volume. Spikes correlate with Ordinals waves and congestion events.
What is it?
Average Block Size measures the mean weight in bytes of blocks mined over the last 24 hours. This metric is a fundamental indicator of block space demand: the more users want to transact, the fuller blocks get. The theoretical SegWit limit is ~4 MW (megaweights), roughly 4 MB in raw equivalent, but in practice blocks rarely reach this maximum because transaction composition (witness/non-witness ratio) varies. Standard transactions, Ordinals inscriptions, OP_RETURN data, and consolidations all contribute to block size.
How to read
Blocks near maximum capacity (~1.5-2.5 MB average) indicate strong demand and high fees. Small blocks (<500 KB) mark low network activity and minimal fees. The long-term trend is structurally upward since SegWit activation (2017) and the Ordinals era (2023). Regimes above 1.5 MB average reflect sustained capacity utilisation; drops below 1 MB correspond to inscription-disengagement phases.
Key zones
Pre-SegWit (before 2017): blocks were hard-limited to ~1 MB. Post-SegWit: average gradually climbed to 1.2-1.5 MB. Ordinals era (2023+): peaks at 2-2.5 MB during inscription waves. Historical range spans from ~215 bytes (near-empty early blocks) to ~2.5 MB (maximum congestion).
What to observe
Correlate average block size with feerates: full blocks + high fees = real congestion. Full blocks + low fees = low-value transactions (spam, consolidation). Watch the 30d MA trend to detect structural changes in network usage. Sustained size >2 MB would mark capacity approaching its limits.
Historical context
Bitcoin block size has been at the centre of the scalability debate since 2015. The 'Block Size War' resulted in SegWit activation in August 2017, increasing effective capacity without changing the base 1 MB limit. The Ordinals era (2023) filled this additional capacity with non-financial data, reigniting debate about optimal block space usage. Average block size has become a barometer of tension between competing uses.
Expert notes
Data comes from a full node Bitcoin via the block_size_average_24h aggregation (rolling average over 144 blocks). The distinction between raw size (bytes) and SegWit weight (weight units) matters: a 2 MB block in bytes can weigh 4 MW in weight units if witness-dominant. This metric uses raw bytes for readability. Observed range spans 215 to ~2.5M bytes.
Common mistakes to avoid
Bigger blocks do not mean 'Bitcoin is slow' - block size does not affect inter-block time (~10 min average). Confusing size with weight is common: SegWit decoupled these two measures. Additionally, high average size is not negatively correlated with decentralisation - bandwidth and storage requirements remain modest even at 2+ MB/block.
Programmatic access
REST API
curl -sS \
'https://api.trinityinsights.io/api/v1/onchain/average-block-size/history?days=90' \
-H 'X-API-Key: $TRINITY_API_KEY'MCP server
{
"tool": "get_chart_value",
"metric_id": "average-block-size",
"timeframe": "1y"
}Required tier: pro. See the pricing grid for the tier list and the MCP documentation for multi-client configuration.
Related metrics
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.