How big is a transaction?

Examples

How it is calculated

• Header: 12 bytes (version, flags and lock height), plus one count each for inputs, outputs and authorizations (1 byte each up to 252 items).
• Each input: 40 bytes to point at the coin being spent, plus its authorization. With ML-DSA-87 that is 7,225 bytes: a 2,592-byte public key and a 4,627-byte signature. With SLH-DSA-SHAKE-256s it is 29,863 bytes: a 64-byte public key and a 29,792-byte signature.
• Each output: 44 bytes to a normal address, 82 bytes to an address with a recovery key. The calculator uses normal addresses.
• Coins with a recovery key: spending them the normal way takes 1 more byte per input. The recovery path only opens once the delay set in the address has passed, between 144 and 5,256,000 blocks.
• Minimum fee: 1 joma per byte, the node default. A node can be set to ask for more. 1 tQAN is 100,000,000 jomas.
• Limit per transaction: to enter the mempool, a transaction may not exceed 20,000 verify units. Each ML-DSA-87 signature counts 290 and each SLH-DSA-SHAKE-256s signature 3,600: at most about 68 normal inputs or 5 recovery inputs.
• Time: the sum of about 55 µs per ML-DSA-87 signature and 1.2 ms per SLH-DSA-SHAKE-256s signature on an x86-64 server, and 167 µs and 1.9 ms on ARM, from the published measurements (x86-64, ARM). It counts signatures only.

One input and two outputs give 7,368 bytes, the same size the node reports for a real transaction. With elliptic-curve signatures, the key and signature of one input take about 100 bytes; with ML-DSA-87, 7,219. The post-quantum signatures page explains why.

The calculator runs in your browser and sends nothing.