What Is the Difference in Size between a Standard Single-Signature and a Multi-Signature Transaction?

A multi-signature (multisig) transaction is significantly larger in size than a standard single-signature transaction. A multisig transaction requires multiple digital signatures to authorize the spending of funds, and all these signatures must be included in the transaction data.

Since each signature adds data (witness data), a 2-of-3 multisig transaction, for example, will be much larger than a standard single-key transaction. This larger size means a multisig transaction will require a higher total fee to achieve the same fee-per-byte rate.