Calculating your Bitcoin transaction fee is straightforward once you know two numbers: your transaction size in virtual bytes (vB) and the current sat/vB fee rate. The formula is: Total Fee (satoshis) = Transaction Size (vB) × Fee Rate (sat/vB). Multiply the result by the current BTC price to get the fee in fiat currency.
Transaction sizes vary by address type and complexity. A 1-input 2-output legacy P2PKH transaction is approximately 250 vB. The same transaction using SegWit (P2WPKH, bc1q address) is about 140 vB — a 44% reduction. A Taproot transaction (P2TR, bc1p address) is approximately 110 vB. Using modern address types directly reduces your fee at any given sat/vB rate.
Example calculations at common fee rates: At 10 sat/vB — SegWit (140 vB) = 1,400 sats (~$0.56 at $40K BTC). At 30 sat/vB — SegWit (140 vB) = 4,200 sats (~$1.68 at $40K BTC). At 100 sat/vB — SegWit (140 vB) = 14,000 sats (~$5.60 at $40K BTC). Multi-input transactions (e.g., consolidating UTXOs) are larger: 10-input SegWit is ~550 vB.
Example calculations at common fee rates: At 10 sat/vB — SegWit (140 vB) = 1,400 sats (~$0.56 at $40K BTC). At 30 sat/vB — SegWit (140 vB) = 4,200 sats (~$1.68 at $40K BTC). At 100 sat/vB — SegWit (140 vB) = 14,000 sats (~$5.60 at $40K BTC). Multi-input transactions (e.g., consolidating UTXOs) are larger: 10-input SegWit is ~550 vB.
Note: these fee values scale linearly with BTC price. At $80,000/BTC, double the USD amounts shown. Always check real-time mempool conditions before sending to ensure you use the current market rate.
To minimize fee costs: use SegWit or Taproot addresses, consolidate UTXOs during low-fee periods, batch multiple payments into one transaction when possible, and send during weekend hours when the mempool often clears to 1-3 sat/vB. These strategies combined can reduce fees by 70% or more compared to using legacy addresses at peak-hour rates.
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