Mempool
TL;DR
The mempool is the waiting room for Bitcoin transactions: all pending transactions awaiting inclusion in a block.
Each Bitcoin node maintains a mempool — transactions validated but not yet in a block. Miners pick transactions from the mempool by fee density (sats/vByte). During congestion, incoming transactions exceed block capacity; fees rocket. In calm periods you can still get confirmed at 1-2 sat/vB within hours.
Example
During an ordinals spike in 2023-2024 the mempool filled up; some transactions paid >500 sat/vB or €50+. In quiet periods: 1-3 sat/vB, €0.10 per transaction.
Frequently asked questions
What if my transaction waits too long?
After 2 weeks most nodes drop it. Via Replace-By-Fee (RBF) you can raise the fee so miners pick it up.
Related terms
Further reading
- → Our service: Bitcoin sector