The number of OP_RETURN outputs on the Bitcoin network is approaching 700,000, nearing all-time highs. This growth is primarily driven by the Runes protocol, which uses OP_RETURN to store token data directly on the base layer.
The Bitcoin Core v30 update, released on October 10, 2025, increased the default relay policy limit for OP_RETURN data from 83 bytes to approximately 100 kilobytes. The update also enabled the use of multiple OP_RETURN outputs within a single transaction.
Daily transaction counts on the network exceeded 800,000 at peak times. Data from CryptoQuant for June 2026 indicates that about 80% of this volume consists of micro-transactions valued at less than 0.01 BTC.
In June 2026, mempool congestion reached approximately 128,000 pending transactions. Despite this, median transaction fees remain low, as these data-heavy transactions are typically low-priority and do not compete for high fee rates.
Mining pools are adapting by prioritizing larger OP_RETURN batches to optimize yields. Meanwhile, the community is discussing BIP-110, a proposal aimed at formalizing rules for blockspace allocation and transaction prioritization.
