21Relay utility

Bitcoin Transaction Size Calculator

Estimate virtual size and compare total fees across common address types, input counts, output counts and multisig configurations.

Detail level

Guided mode keeps the decision focused. Advanced mode reveals extra assumptions.

Keep in mind: This is a planning estimate, not a transaction serializer. Exact signatures, scripts, annexes and wallet behaviour can change final weight.

Transaction structure

Quick starts

InputsOutputsInput/address typeRequired signatures (m)Total keys (n)Fee rates to compare (sat/vB)

Estimated virtual size

Compact transaction

This structure is relatively compact. Final wallet construction can still change the signed size.

Use this estimate in the Fee Estimator →

Estimated virtual size

~209 vB

Configuration

Single signature

Inputs

Outputs

At 1 sat/vB209 sats

At 2 sat/vB418 sats

At 5 sat/vB1,045 sats

At 10 sat/vB2,090 sats

At 25 sat/vB5,225 sats

Methodology, data and limits

This is a planning estimate, not a transaction serializer. Exact signatures, scripts, annexes and wallet behaviour can change final weight.
Taproot multisig can use aggregated key-path or script-path spending; this calculator uses a compact planning approximation.
The fee is virtual size multiplied by fee rate. Confirmation remains probabilistic.

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