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Mempool Statistics

Bitcoin Knots includes a visual mempool statistics widget — a feature that was in older Bitcoin Core versions but removed. The old_stats_qt patch restores and enhances this functionality.

Accessing Mempool Stats​

Menu: Window → Mempool Statistics

The mempool stats window appears above the debug window entries in the menu.

Features​

Real-Time Metrics​

MetricDescription
TX CountNumber of unconfirmed transactions
Virtual SizeTotal vbytes of mempool transactions
Memory UsageRAM consumed by mempool
Min Fee RateLowest fee rate to get into mempool
Loading ProgressShows progress when mempool is loading

Fee Histogram​

Visual distribution of transactions by fee rate, showing:

  • Number of transactions in each fee bracket
  • Total size/weight per bracket
  • Helps estimate confirmation times

Min Relay Fee Fallback​

When the mempool is empty, the stats display uses the minimum relay fee as a reference point — a v29.2 enhancement that prevents confusing zero displays.

RPC Equivalent​

The same data is available programmatically:

# Basic mempool info
bitcoin-cli getmempoolinfo

# Example output:
{
  "loaded": true,
  "size": 12345,
  "bytes": 5678901,
  "usage": 23456789,
  "total_fee": 0.12345678,
  "maxmempool": 300000000,
  "mempoolminfee": 0.00001000,
  "minrelaytxfee": 0.00001000
}

Enhanced getmempoolinfo (Knots)​

Knots adds a fee histogram to mempool info:

bitcoin-cli getmempoolinfo

The response includes fee distribution data not available in Bitcoin Core.

Configuration​

Mempool Size​

bitcoin.conf
# Maximum mempool size in MB (default: 300)
maxmempool=300

# Mempool expiry in hours (default: 336 = 2 weeks)
mempoolexpiry=336

Fee Estimation​

bitcoin.conf
# Minimum relay fee (affects what enters mempool)
minrelaytxfee=0.00001

# Save fee estimates to disk (Knots feature)
# Use RPC: bitcoin-cli savefeeestimates

Use Cases​

  • Fee estimation: See current fee landscape before sending
  • Network health: Monitor transaction volume and backlog
  • Debugging: Identify mempool issues affecting your node
  • Research: Study transaction patterns

See Also​