Transaction Fee Calculator (Crypto)

Tips

• Transaction size is in virtual bytes (vB). If you have weight units (wu), divide by 4.
• SegWit spends are smaller than legacy; taproot single-sig is smaller again.
• Fee rate is usually quoted in sat/vB by wallets and mempool explorers.
• Set your own BTC price to value the fee in your currency; we don’t fetch prices.

How Bitcoin-style transaction fees work

Bitcoin and many UTXO-based chains use a fee market: miners prioritize transactions offering the highest fee per unit of block space. That unit is usually sat/vB (satoshis per virtual byte). Your total fee equals tx size (vbytes) × fee rate (sat/vB). This calculator does that arithmetic locally and also converts to BTC and your chosen fiat using a price you enter (no APIs).

Transaction size depends on how many inputs you spend and what script types they use. Legacy transactions are bigger; SegWit reduces weight; taproot single-sig is smaller still. A common 1-in/2-out P2WPKH spend is roughly 110 vB, while a 2-in/2-out legacy spend might be ~220 vB. If a wallet shows weight units (wu), divide by four to estimate vbytes. Fee estimation services and mempool explorers usually quote sat/vB targets for “fast/medium/slow,” but you can also derive your own rate from recent blocks and mempool backlog.

Underpaying the fee risks being stuck in the mempool for hours or days. If that happens on Bitcoin, you can try RBF (Replace-By-Fee) if your wallet marked the transaction replaceable, or CPFP (Child-Pays-For-Parent) by spending a change output with a higher fee rate so the combined package meets miner targets. Overpaying wastes sats, so watching recent block data and setting a fee aligned with congestion is best. Remember that a transaction is only confirmed once it appears in a block; zero-conf acceptance is at the receiver’s risk.

Fees scale linearly with size: each extra input adds dozens of bytes, while extra outputs add less. Consolidating small UTXOs when fees are low can reduce future costs because you’ll have fewer inputs to spend later. Conversely, sweeping many tiny inputs during a fee spike can be expensive. For chains with dynamic block limits or EVM-style gas, the concept is similar—fee rate × size— even though the units (gas price, gwei) and size accounting differ.

This tool is static and privacy-first: no price feeds, no storage, no network calls. Enter your own sat/vB rate, transaction size, and BTC price to value the fee where you live. If you want a faster confirmation, increase the fee rate; if you can wait, lower it and monitor the mempool. Always verify the exact size your wallet reports before broadcasting.