Complete Guide to Japanese Zenkaku & Hankaku for Banking and Registration
Why do Japanese banks still require half-width Katakana? Learn the history of Zenkaku/Hankaku and how to correctly format your name for Japanese forms.
In Japan, a single 'Invalid Character' error can block your bank transfer or membership application. This is often caused by the confusing distinction between Zenkaku (Full-width) and Hankaku (Half-width) characters. This guide explains why this distinction exists and how to navigate Japanese digital forms like a pro.
The Difference: Zenkaku (Full-width) vs. Hankaku (Half-width)
Visually, Zenkaku characters fit into a perfect square, whereas Hankaku characters are half as wide. Technically, Zenkaku characters occupy 2 bytes (16 bits) of data, while Hankaku characters occupy only 1 byte (8 bits). This legacy of 8-bit computing is what defines modern Japanese form requirements.
Why Banks Still Demand Half-width Katakana
Japan's inter-bank network (Zengin System) was established decades ago. To save space on expensive mainframe storage, they allocated only 1 byte per Katakana character. Even today, while websites look modern, the underlying data must be sent to the Zengin network in this 1-byte format. If you enter 'Zenkaku' (2-byte) characters, the system cannot process the request.
How to Identify and Fix Form Errors
When a form asks for 'フリガナ (半角)', it strictly requires 1-byte characters. A common pitfall is the space between your first and last name; it must also be a half-width space. Our converter handles this by normalizing spaces and splitting complex Katakana into their base and mark components.