A kodachi is a traditional Japanese sword characterized by its shorter length compared to a standard katana. The blade length of a kodachi typically falls within the range of 18 to 24 inches (45 to 61 centimeters).

The exact length of a kodachi can vary based on the specific sword and individual preferences, but it is generally shorter than a katana and longer than a tanto (a shorter dagger-like blade). The shorter length of the kodachi allows for greater maneuverability in close-quarters combat or indoor environments.

The kodachi was historically used as a secondary weapon or for specific combat situations that required a shorter blade. It offered a balance between reach and control, allowing for versatile fighting techniques.

It's important to note that the measurements provided are approximate and can vary between individual kodachi swords due to variations in historical examples, regional traditions, and personal tastes of sword owners or collectors.

In summary, the blade length of a kodachi typically falls within the range of 18 to 24 inches (45 to 61 centimeters), making it shorter than a katana but longer than a tanto. The kodachi serves as a versatile and maneuverable sword suitable for close-quarters combat and specific combat situations.