BitcoinMachine
TERM_DEF // TRANSACTION / FEERATE
FEERATE
Feerate. Fee divided by transaction virtual size; what miners actually sort by when filling blocks.

This page sits in the Transaction section — How money moves: inputs, outputs, fees, signatures, sighash flags, and the formats that wrap them. Read on for what it is, why it exists, how it works under the hood, and what to watch out for.
WHAT_FEERATE_IS
Feerate — at a glance
TRANSACTION
Feerate is part of the FEE ECONOMY sub-family of transaction-level concepts. Fee paid per virtual byte of transaction size (sat/vB) — the actual price miners use to rank txs for inclusion. Fee divided by transaction virtual size; what miners actually sort by when filling blocks.
Why it exists
DESIGN
Bitcoin's block-space auction has limited supply (~1.7M vbytes per block) and unlimited demand. Sorting by absolute fee would unfairly favour large transactions; sorting by feerate prices each byte fairly.
HOW_IT_WORKS
Mechanism
HOW IT WORKS
feerate = fee_sats / virtual_size_vbytes. Miners build blocks by sorting mempool by feerate descending and packing until full. The "next block" feerate at any moment is the boundary value — pay above it for fast confirmation.
1. Wallet selects UTXOs whose total value covers the spend amount + estimated fee (coin selection). 2. Wallet builds the transaction body: version, inputs (each with prev txid + vout + sequence), outputs (each with value + scriptPubKey), locktime. 3. Wallet computes the sighash for each input (which parts of the tx the signature commits to — controlled by the SIGHASH flag). 4. Wallet signs each input with the right private key. Witness/scriptSig is populated with the resulting signatures + pubkeys. 5. Tx is broadcast to peers. Mempool propagation: tens of seconds globally. 6. A miner includes it in a block. Confirmation count grows by 1 per block; after ~6 the tx is effectively final.
WORKED_EXAMPLE
Feerate — FEE ECONOMY
EXAMPLE
Example tx size fee feerate small P2WPKH transfer 140 vB 2,800 20 sat/vB multisig redemption 250 vB 5,000 20 sat/vB large CoinJoin (10 hops) 1,500 vB 45,000 30 sat/vB Mempool view : mempool.space, mempool.observer, bitcoin-cli getmempoolinfo Fee estimator : bitcoin-cli estimatesmartfee 6 → feerate for ~6 block confirm
KEY_PROPERTIES
PER-VBYTE
Miners rank by sat/vB, not absolute fee. A 2,000-vbyte tx paying 20,000 sats (10 sat/vB) loses to a 200-vbyte tx paying 6,000 sats (30 sat/vB).
ATOMIC
A transaction is either fully accepted into a block or fully rejected. There is no partial spend.
IMMUTABLE INPUTS
A UTXO can only ever be spent once. After that, it is permanently consumed.
NO BALANCES
Bitcoin tracks UTXOs, not balances. Your wallet computes a balance by summing the UTXOs it controls.
COMMON_PITFALLS
Things that catch people out
PITFALLS
  • address-reuse/">Address reuse degrades privacy — every reuse links more of your UTXOs together publicly. Modern wallets generate a fresh address per receive.
  • Fee estimation matters: under-pay and your tx sits in the mempool for hours; over-pay and you tip the miner more than necessary. Use a fee estimator.
  • "Change outputs" must go back to a fresh address you control. A missing output/">change output sends the difference to the miner as fee — a known footgun.
  • RBF (Replace-By-Fee) lets you re-broadcast a tx with a higher fee. Useful for stuck txs but means a 0-confirmation tx is never truly final.
RELATED_CONCEPTS
Other terms from Transaction — click any to read its page:
Transaction (Tx) Raw Transaction Transaction ID (TXID) wTXID (Witness TXID) Input Output UTXO (Unspent Transaction Output) UTXO Set
TERMINOLOGY_INDEX
TERMINOLOGY
Feerate
Fee divided by transaction virtual size; what miners actually sort by when filling blocks.
Transaction (Tx)
A signed payload spending one or more UTXOs and creating new ones; every state change in Bitcoin is a tx.
Raw Transaction
The hex-serialized bytes of a transaction, ready to broadcast or analyze.
Transaction ID (TXID)
HASH256 of a transaction's pre-witness serialization; used to reference outputs by (txid, vout).
wTXID (Witness TXID)
HASH256 of the full transaction including witness data; commits to signatures and used in the witness commitment.
Input
A reference to a previous output being spent, plus the data (scriptSig/witness) authorizing the spend.
Output
An (amount, scriptPubKey) pair created by a transaction; spendable later by a tx whose input references it.
UTXO (Unspent Transaction Output)
An output that hasn't been spent yet; your "balance" is the sum of UTXOs you can sign for.