A "tanto katana" is not a recognized or standard term in the context of Japanese swords. The terms "tanto" and "katana" refer to two distinct types of blades with different characteristics.

A tanto is a traditional Japanese dagger or short sword with a blade length typically falling under 12 inches (30 centimeters). It has a straight or slightly curved blade and is primarily designed for stabbing and close-quarters combat.

On the other hand, a katana is a longer Japanese sword with a curved, single-edged blade. The average blade length of a katana is around 27 to 30 inches (69 to 76 centimeters), although the exact length can vary.

It's important to note that tanto and katana are separate categories of swords, each with their own unique features, purposes, and historical contexts. While it's possible for a sword to have characteristics that combine elements of tanto and katana, the specific length and design would depend on the individual sword and the preferences of the swordsmith or owner.

In summary, tanto and katana are distinct types of Japanese swords with different blade lengths and characteristics. A "tanto katana" is not a recognized term, and any sword combining elements of tanto and katana would be a unique or custom creation with its own specific dimensions and design.