Japanese Swords - Classification - Length

Length

What generally differentiates the different swords is their length. Japanese swords are measured in units of shaku. Since 1891, the modern Japanese 'shaku' is approximately equal to a foot (11.93 inches), calibrated with the meter to equal exactly 10 meters per 33 shaku (30.30 cm).

However the historical shaku was slightly longer (13.96 inches or 35.45 cm). Thus, there may sometimes be confusion about the blade lengths, depending on which shaku value is being assumed when converting to metric or US measurements.

The three main divisions of Japanese blade length are:

• 1 shaku or less for tantō (knife or dagger).
• 1–2 shaku for Shōtō (小刀:しょうとう?) (wakizashi or kodachi).
• 2 shaku or more for daitō (大刀?) (long sword, such as katana or tachi).

A blade shorter than one shaku is considered a tantō (knife). A blade longer than one shaku but less than two is considered a shōtō (short sword). The wakizashi and kodachi are in this category. The length is measured in a straight line across the back of the blade from tip to munemachi (where blade meets tang). Most blades that fall into the "shōtō" size range are wakizashi. However, some daitō were designed with blades slightly shorter than 2 shaku. These were called kodachi and are somewhere in between a true daitō and a wakizashi. A shōtō and a daitō together are called a daishō (literally, "big and small"). The daishō was the symbolic armament of the Edo period samurai.

A blade longer than two shaku is considered a daitō, or long sword. To qualify as a daitō the sword must have a blade longer than 2 shaku (approximately 24 inches or 60 centimeters) in a straight line. While there is a well defined lower-limit to the length of a daitō, the upper limit is not well enforced; a number of modern historians, swordsmiths, etc. say that swords that are over 3 shaku in blade length are "longer than normal daitō" and are usually referred to or called ōdachi. The word "daitō" is often used when explaining the related terms shōtō (short sword) and daishō (the set of both large and small sword). Miyamoto Musashi refers to the long sword in The Book of Five Rings. He is referring to the katana in this, and refers to the nodachi and the odachi as "extra-long swords".

Before 1500 most swords were usually worn suspended from cords on a belt, edge-down. This style is called jindachi-zukuri, and daitō worn in this fashion are called tachi (average blade length of 75–80 cm). From 1600 to 1867, more swords were worn through an obi (sash), paired with a smaller blade; both worn edge-up. This style is called buke-zukuri, and all daitō worn in this fashion are katana, averaging 70–74 cm (2 shaku 3 sun to 2 shaku 4 sun 5 bu) in blade length. However, nihontō of longer lengths also existed, including lengths up to 78 cm (2 shaku 5 sun 5 bu). The weight of a nihontō rarely exceeded 1 kg without the saya.

It was not simply that the swords were worn by cords on a belt, as a 'style' of sorts. Such a statement trivializes an important function of such a manner of bearing the sword. It was a very direct example of 'form following function.' At this point in Japanese history, much of the warfare was fought on horseback. Being so, if the sword/blade were in a more vertical position, it would be cumbersome, and awkward to draw. Suspending the sword by 'cords,' allowed the sheath to be more horizontal, and far less likely to bind while drawing it in that position.

A chisa katana (小さ刀, chiisa gatana?) is simply a shorter nihontō. It is longer than the wakizashi, usually about 18 inches in length. The most common reference to a chisa katana is a shorter nihontō that does not have a companion blade. They were most commonly made in the buke-zukuri mounting.

Abnormally long blades (longer than 3 shaku), usually carried across the back, are called ōdachi or nodachi. The word ōdachi is also sometimes used as a synonym for nihontō. Odachi means "Great Sword", and Nodachi translates to "Field sword". Nodachi were used during war as the longer sword gave a foot soldier a reach advantage, but now nodachi are illegal because of their effectiveness as a killing weapon. Citizens are not allowed to possess an odachi unless it is for ceremonial purposes.

Here is a list of lengths for different types of swords:

• Nodachi, Ōdachi, Jin tachi: 90 cm and over (more than three shaku)
• Tachi, Katana: over 60.6 cm (more than two shaku)
• Wakizashi: between 30.3–60.6 cm (between one and two shaku)
• Tantō, Aikuchi: under 30.3 cm (under one shaku)

Swords whose length is next to a different classification type are described with a prefix 'O-' (for great) or 'Ko-' (for small), e.g. a Wakizashi with a length of 59 cm is called an O-wakizashi (almost a Katana) whereas a Katana with 61 cm is called a Ko-Katana (for small Katana) .

Since 1867, restrictions and/or the deconstruction of the samurai class meant that most blades have been worn jindachi-zukuri style, like Western navy officers. Since 1953, there has been a resurgence in the buke-zukuri style, permitted only for demonstration purposes. Swords designed specifically to be tachi are generally kotō rather than shintō, so they are generally better manufactured and more elaborately decorated, however, these are still katana if worn in modern buke-zukuri style.