Moving to Japan: The Expat Calculation Guide

Japan is one of the world's most rewarding places to live — but it comes with a unique administrative culture that can trip up even the most prepared expat. Documents use Japanese eras instead of Western years, apartments are measured in tatami mats and tsubo, and local colleagues may casually mention your yakudoshi (unlucky years). Here's how to navigate it all.

Step 1: Master the Japanese Era System

The moment you land, Japanese paperwork will ask for your date of birth in the wareki (和暦) format. For example, if you were born in 1994, that's Heisei 6 (平成6年). Japan's current era, Reiwa (令和), began on May 1, 2019.

Use Wareki to convert any Western (Gregorian) year to its Japanese era equivalent — and vice versa. This is essential for: - Residence card (在留カード) applications - Bank account openings - Driver's license conversion - Health insurance enrollment (国民健康保険)

Save a screenshot of your birthday in wareki format on your phone. You'll use it constantly in the first few months.

Step 2: Decode Apartment Size Listings

Japanese apartment listings use two units that will look foreign at first: tsubo (坪) and tatami (畳). Searching for a 1LDK in Tokyo, you'll see listings like "25㎡" alongside "15.1坪" and "8畳." These measure the same space three different ways.

Tsubo Converter converts between tsubo, tatami mats, square meters, and square feet. As a reference: a standard Tokyo studio apartment is typically 20–30㎡, roughly 6–9 tsubo, or 12–18 tatami mats.

When touring apartments, bring a tape measure and remember: tatami room sizes vary slightly by region (Kyoto tatami is larger than Tokyo tatami). Always confirm the square meter figure on the official floor plan.

Step 3: Track Your Age (and Unlucky Years)

Age calculates both your international age and confirms your age in Japanese counting systems. Japan officially uses Western-style age (満年齢, man-nenrei) for legal purposes, so your standard age applies everywhere.

However, Japan also has a cultural tradition called yakudoshi (厄年) — specific ages considered spiritually unlucky. Yakudoshi checks whether your current age falls in a yakudoshi year. For men, the major unlucky year is 42; for women, 33. Many Japanese people visit a shrine for purification (厄払い, yakubarai) during these years.

You don't need to believe in it, but understanding it helps you connect with colleagues and neighbors. If your coworker mentions they're having their 厄払い ceremony, you'll know exactly what they mean.

Practical Tokyo Apartment Checklist

Japan rewards patience and preparation. Once you have the language of Japanese dates, room sizes, and cultural milestones, daily life becomes significantly smoother.