Mempool & Fees

What it costs to get a Bitcoin transaction confirmed right now, and how much is queued up waiting.

Common questions

What is the mempool?

Every transaction that has been broadcast but not yet included in a block. Miners pick from it, highest fee rate first, so the mempool is both the waiting room and the auction.

Why are fees measured in sat/vB rather than dollars?

Because miners are selling space, not value. A transaction's cost depends on how many bytes it occupies, so moving 0.001 BTC and moving 1,000 BTC cost the same if they are the same shape. Consolidating many small inputs is expensive for exactly this reason.

Can a transaction be stuck forever?

It can sit for a long time. Nodes drop transactions from their mempool after a couple of weeks, at which point it is as if it was never sent. Wallets that support replace-by-fee can rebroadcast the same transaction with a higher fee instead of waiting.