One-Sentence Definition
A transaction fee is the extra payment users attach to their cryptocurrency transactions to incentivize miners to include them in the next block.
Why It Matters for Solo Mining
When you solo mine and actually find a block, you get both the block reward and all the transaction fees from every transaction you include—this can add up to a significant bonus on top of your base reward. During busy network periods, transaction fees can sometimes be worth more than the block reward itself, making that rare solo mining win even sweeter. Unlike pool mining where fees get split among everyone, solo miners keep 100% of the transaction fees from their block.
How It Works
When someone sends cryptocurrency, they can attach a fee to make their transaction more attractive to miners. Miners running a full node collect these pending transactions into a “mempool” and then choose which ones to include in their block candidate. Obviously, miners prioritize transactions with higher fees because they want to maximize their earnings—it’s just smart business.
The fee amount is calculated based on the transaction’s data size (measured in bytes) and how urgently the sender wants it confirmed. During congestion, people compete by offering higher fees, which is why you sometimes see Bitcoin transaction fees spike from a few cents to $50+ during crazy bull markets. Once a miner includes your transaction in a block and that block gets added to the blockchain, the miner collects all those fees as part of their reward.
Different cryptocurrencies handle fees differently—Bitcoin users set fees manually (or via wallet estimates), Ethereum used to have gas fees that could get insane, and some newer chains have more predictable fee structures.
Example
Imagine you’re solo mining Bitcoin and you finally hit a block at the current 3.125 BTC block reward. If the network is busy and you’ve included 2,000 transactions with an average fee of 0.0001 BTC each, you’d earn an extra 0.2 BTC in transaction fees—that’s about $13,000 extra at current prices! In May 2026, one Bitcoin block contained over 6 BTC in fees alone because of high demand for ordinals inscriptions.
Related Terms
- Block Reward – The fixed amount of new cryptocurrency created with each block
- Mempool – The waiting area where unconfirmed transactions sit before miners include them
- Full Node – Software that validates transactions and maintains the complete blockchain
- Confirmation – When a transaction gets included in a block and added to the blockchain
- Satoshi per Byte (sat/vB) – Common unit for measuring Bitcoin transaction fees