The handle of a katana, also known as the tsuka, typically measures around 10 to 12 inches (25 to 30 centimeters) in length. The tsuka is an integral part of the katana and provides a grip for the wielder's hand.

The length of the tsuka can vary based on individual preferences, hand size, and the specific design of the sword. Some katana may have slightly shorter or longer handles, but the average length falls within the mentioned range.

The tsuka is traditionally wrapped with a material called tsukamaki, which provides a comfortable and secure grip. The wrapping may consist of silk or cotton cord, known as ito, and is skillfully applied by craftsmen.

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

In summary, the length of a katana handle, or tsuka, typically falls within the range of 10 to 12 inches (25 to 30 centimeters), providing a suitable grip for the wielder's hand. However, variations can exist based on individual preferences and the specific design of the sword.