Sword Size Guide — Differences Between Tachi, Katana, Wakizashi, and Tanto
* Image is for illustrative purposes only.Table of Contents
The Dimensional System of Japanese Swords: Blade Length Tells the History and Purpose of the Sword
When discussing Japanese swords, dimensions are far more than mere numbers. Measurements such as blade length (hachou), curve (sori), width at the base (motohaba), width at the point (sakihaba), and thickness eloquently tell us when, where, and for what purpose a given sword was crafted. When appreciating, purchasing, or collecting swords, it is essential to understand how to read these dimensions.
In Japan, the traditional shaku-kan system is used for sword measurements. 1 shaku ≈ 30.3 cm, 1 sun ≈ 3.03 cm, 1 bu ≈ 3 mm. If a blade length is listed as "2 shaku 3 sun 5 bu," that calculates to approximately 71.3 cm. Since dealer catalogs and certification documents still use this notation today, it's important to memorize these basic conversions.
---
Tachi—The Long-Bladed Masterpieces Chosen by Kamakura Warriors
A tachi is defined as having a blade length of 2 shaku (approximately 60.6 cm) or more and bearing a signature on the side that faces outward when suspended from the waist (hakyomote). The hakyomote refers to the face that points outward when the sword is hung at the waist. The tachi employs the "haitou" mounting style, where the blade points downward and is suspended by a metal fitting threaded through the belt.
Historically, the tachi is characterized by a curve (sori) that is deep relative to the blade length; it is not uncommon for a tachi with a 70 cm blade to have a curve of 2–2.5 cm. This pronounced curve is a shape optimized for downward cuts from horseback, and the tachi reached its peak during the late Heian through Nanboku-Chō periods, when mounted samurai dominated the battlefield.
Famous examples of tachi include the "Dojigiri Yasutuna" (blade length approximately 79.8 cm) crafted by the Bizen Osafune school, and the "Mikazuki Munechika" (blade length approximately 80 cm), designated as a National Treasure. Both possess deep sori and maintain their original form without major polishing, making them exceptionally rare masterpieces.
---
Uchigatana—The Practical Mainstream That Defined the Sengoku Period
Like the tachi, the uchigatana has a blade length of 2 shaku or more, but the decisive difference is that it employs the "sashiryo" style, where the blade is oriented upward and thrust through the waist belt. The rapid-draw and cutting technique known as "battōjutsu" (iaijutsu) became possible precisely because of this way of wearing the uchigatana.
When infantry footsoldiers (ashigaru) rose to prominence during the Muromachi period, ground-based melee combat increased dramatically, and the more maneuverable uchigatana rapidly spread. Compared to the tachi, it has a shallower curve (approximately 1–1.5 cm), and its center of gravity is positioned closer to the hilt, giving it superior cutting speed and handling. The most common blade length is around 2 shaku 3 sun (approximately 70 cm), also called the "jōsun" or standard length.
A form with a smaller difference between base width and point width—characteristic of fewer curves—became fashionable from the mid-Edo period onward. Conversely, the "Keichō Shintō" (new swords of the late Sengoku and early Edo periods) typically feature a broad base width and a robust construction. Even among swords that are technically "uchigatana with a 70 cm blade," the form differs dramatically by era. Learning the correspondence between form and period is one of the great pleasures of sword appreciation.
---
Wakizashi—The "Short" of the Daishō, Playing Many Roles
The wakizashi is defined as having a blade length of 1 shaku or more but less than 2 shaku (approximately 30–60 cm). During the Edo period, samurai maintained the custom of wearing both an uchigatana and a wakizashi together, a pairing known as "daishō" (large and small), with the wakizashi representing the "small" element.
Wakizashi are sometimes further subdivided by blade length: those around 1 shaku 5 sun (approximately 45.5 cm) are called chū-wakizashi (medium wakizashi), and those around 1 shaku 8 sun (approximately 54.5 cm) are called ō-wakizashi (large wakizashi). Among large wakizashi, some are visually almost indistinguishable from uchigatana, and determining this subtle boundary is one of the key points of authentication.
The applications of the wakizashi were diverse. It was used in close-quarters combat in indoor and confined spaces, as well as in ritual suicide (kaishauku). There was also a court etiquette whereby one would entrust a longer blade to one's lord but could keep the wakizashi thrust at the waist—making the wakizashi an indispensable complement to the uchigatana. For modern collectors, the wakizashi is popular because it does not demand much storage space, and many examples feature elaborate koshirae (mounting) designs.
---
Tanto—Where the Oldest Form Houses the Essence of the Sword
The tanto is defined as having a blade length under 1 shaku (approximately 30 cm or less). Production of the tanto is documented from the Heian period onward, making it among the oldest categories of sword forms. It typically has little to no curve—many are made in the "hira-zukuri" (flat construction) style—though some possess a subtle inward curve (uchizori).
Beyond being widely used for self-defense, the tanto was also popular as a "kaiken" (concealed short blade) carried by women in their clothing. The custom of a bride bringing a tanto as part of her wedding trousseau persists in modern times, carrying significant symbolic meaning. The "sasuga," used in ritual suicide, is also a type of tanto.
The construction of the tanto is delicate, allowing the jigane (ground metal) and hamon (temper pattern) of the blade to be appreciated up close. It is common to encounter a piece in which the swordsmith's skill is concentrated, and many enthusiasts begin their sword appreciation journey with the tanto. With a wide range of prices, it is well-suited for beginners seeking their first blade.
---
Reading Dimensions and Key Points When Purchasing
When actually selecting a sword, be sure to check not only the blade length but also the following measurements.
Motohaba (base width) is the blade width near the hilt-guard area; for an uchigatana, a standard range is approximately 2.8–3.2 cm. The wider it is, the greater the sense of weight and presence. Sakihaba (point width) is the width near the tip; when the difference between motohaba and sakihaba is small, the form appears robust and powerful, while a larger difference creates a more delicate appearance. Kasane (thickness) is the measurement from the back of the blade (muné) toward the tip; the greater the thickness, the greater the weight and durability.
For a first uchigatana purchase, a blade length of 65–72 cm (2 shaku 1 sun to 2 shaku 4 sun) is easy to handle and displays well on a stand. It is also important to measure the space for wall-mounted cases or sword stands in advance and estimate the overall length (blade length + hilt length + scabbard length). Generally, the overall length is approximately 1.5–1.6 times the blade length.
When a wakizashi is paired with a longer blade to form a "daishō koshirae" (matched large-and-small mounting), the display becomes strikingly more beautiful. One approach is to first acquire a single uchigatana and later seek a wakizashi by the same swordsmith from the same era. The tanto is a category that lends itself to comparative appreciation when multiple blades are displayed side by side, making it a category where collectors often expand their numbers.
Dimensions are merely a gateway into the profound world of swords. Once you hold a blade and experience its weight and curve firsthand, you will naturally come to understand the "beauty of form" that numbers alone cannot convey.
