Last updated: October 22, 2026
Bitcoin transaction fees don't depend on how much BTC you send — they depend on how much block space your transaction uses (measured in virtual bytes, vB) multiplied by the fee rate you offer (in satoshis per vB), and that rate rises and falls with demand in the mempool. Pay too little and your transaction can wait for hours; you can then speed it up with Replace-By-Fee (RBF) or Child-Pays-For-Parent (CPFP). Getting fees right matters most when you deposit BTC into a swap like BTC → XMR.
- sat/vB the unit of fee rate
- ~10 min average block time
- Size, not amount, sets the fee
- RBF / CPFP to speed up
How the fee is calculated
Fee = transaction size (vB) × fee rate (sat/vB). Size grows with the number of inputs (coins you spend) and outputs. A typical simple payment with modern addresses is roughly 140–220 vB. Miners pick the highest-paying transactions first, so the rate you need depends on how full the mempool is at that moment. Wallets estimate it for you; mempool explorers show current rates.
What makes a transaction bigger or smaller
| Factor | Effect on fee |
|---|---|
| Many small inputs | Larger transaction — higher fee |
| Native SegWit (bc1q) or Taproot (bc1p) addresses | Smaller than legacy — lower fee |
| Legacy (1…) addresses | Largest — highest fee |
| Multisig | Larger — see multisig |
| Batching several payments | Lower fee per payment |
Address types are explained in crypto address formats.
Stuck transaction? RBF vs CPFP
- Replace-By-Fee (RBF): the sender broadcasts a new version of the same transaction with a higher fee. Most modern wallets offer a "bump fee" button.
- Child-Pays-For-Parent (CPFP): the receiver (or the sender, using the change) spends the unconfirmed output with a high fee, so miners take both together.
- Wait: when demand drops, low-fee transactions confirm eventually or are dropped from mempools, returning coins to your wallet.
For swap deposits, a stuck BTC transaction is the most common reason a swap looks frozen — see crypto swap stuck and swap times.
How to pay lower Bitcoin fees (step by step)
- Use a SegWit or Taproot wallet and addresses.
- Check the mempool before sending; weekends and quiet hours are often cheaper.
- Consolidate small coins when fees are low, so future spends use fewer inputs.
- Don't underpay for time-sensitive sends like fixed-rate swap deposits.
- Consider cheaper chains for moving value: swap BTC to LTC, USDT on Tron or XMR when fees spike — compare on BTC → LTC; Monero fees are tiny (Monero fees).
Frequently asked questions
How are Bitcoin fees calculated?
By transaction size in virtual bytes multiplied by the fee rate in satoshis per vB. The amount of BTC sent doesn't matter.
Why are Bitcoin fees so high sometimes?
Block space is limited. When many people want to transact at once, they bid higher fee rates to get into the next blocks.
How do I speed up a stuck Bitcoin transaction?
Use your wallet's "bump fee" (RBF) option, or CPFP by spending the unconfirmed output with a higher fee.
What fee should I use for a swap deposit?
Use your wallet's normal or priority estimate, especially for fixed-rate orders that have a deposit window.
Is Monero cheaper to send than Bitcoin?
Usually yes — Monero fees are typically fractions of a cent to a few cents. See Monero vs Bitcoin.
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