A mempool fee — short for memory pool fee — is the amount of satoshis per virtual byte (sat/vB) that a Bitcoin user attaches to their transaction to incentivize miners to include it in the next block. Unlike traditional payment systems, Bitcoin fees are not fixed. They are determined entirely by market forces: supply of block space versus demand from users.
When you send Bitcoin, your transaction first enters the mempool — a waiting area of all unconfirmed transactions across the network. Miners then select transactions from the mempool to fill each new block, almost always choosing those with the highest sat/vB rate first. This prioritization system means that paying a higher fee gets your transaction confirmed faster.
The fee itself is implicit. It equals the difference between the total inputs of your transaction and the total outputs. If you send 0.5 BTC from an input worth 0.5001 BTC, the 0.0001 BTC difference is the miner fee. Wallets calculate this automatically and express it as a sat/vB rate.
The fee itself is implicit. It equals the difference between the total inputs of your transaction and the total outputs. If you send 0.5 BTC from an input worth 0.5001 BTC, the 0.0001 BTC difference is the miner fee. Wallets calculate this automatically and express it as a sat/vB rate.
Bitcoin fees are not a tax — they are a market mechanism that allocates scarce block space, incentivizes miners, and will eventually replace block subsidies as Bitcoin's primary security budget.
As of 2026, the average Bitcoin transaction fee is approximately $0.82, with the median around $0.30. During quiet periods, fees can drop to as low as 1 sat/vB. During congestion events — such as price spikes, Ordinals activity, or post-halving demand surges — fees can spike to 100-500+ sat/vB.
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