The mempool (memory pool) is a collection of all unconfirmed Bitcoin transactions waiting to be included in a block by miners.
Understanding the Metrics:
- Pending Transactions: Total number of unconfirmed transactions waiting in the mempool.
- Blocks to Clear: Estimated number of blocks needed to process all pending transactions. Calculated assuming ~2,500 transactions per block (real-world average).
- Virtual Size (vSize): Total size of all transactions in the mempool, weighted for SegWit efficiency. Each block can hold up to ~4 MB vSize.
- Last Block Size: The actual size and vSize of the most recent mined block. Updates every ~10 minutes with each new block.
- Avg Transaction Size: Average size per transaction currently in the mempool. Smaller transactions allow more to fit in each block.
- Fee Rates: Measured in satoshis per virtual byte (sat/vB). Higher fee rates get priority for inclusion in the next block.
Note: The number of transactions per block varies (typically 1,500-3,500) based on transaction types and sizes. SegWit transactions are more space-efficient than legacy transactions. Miners may not always fill blocks to maximum capacity.