Tsubo Converter

If you have ever looked at a Japanese real estate listing, you have almost certainly encountered the term tsubo (坪). This traditional Japanese unit of area is the de facto standard for measuring floor space in Japan, from compact studio apartments to sprawling family homes and commercial properties. Understanding tsubo is essential for anyone planning to rent, buy, or research property in Japan.

One tsubo is approximately 3.30579 square meters, or about 35.58 square feet. Its origins trace back centuries in Japanese history, originally defined as the area covered by two tatami mats laid side by side. That connection to tatami remains culturally significant—one tsubo equals exactly two standard tatami mats (畳, jō).

The Exact Conversion: Tsubo and Square Meters

The precise conversion between tsubo and square meters is defined by the relationship 1 tsubo = 400/121 m², which equals approximately 3.30578512 m². This fraction arises from the historical definition of one shaku (尺), the base Japanese length unit, from which the tsubo is derived. In practice, most real estate materials round this to 3.3058 m² or simply 3.31 m².

To convert tsubo to square meters, multiply the number of tsubo by 3.30579. For example, a 20-tsubo apartment is approximately 66.1 m². To go the other direction—from square meters to tsubo—multiply by the reciprocal, 0.30250. So a 70 m² apartment equals about 21.2 tsubo.

Tatami and Tsubo: A Connected History

The relationship between tatami and tsubo is deeply rooted in traditional Japanese architecture. The standard tatami mat (京間, Kyōma style) measures 1.82 m × 0.91 m, giving an area of about 1.653 m²—exactly half a tsubo. This means that a 6-tatami room (六畳, rokujo) equals 3 tsubo or approximately 9.92 m².

In practice, tatami sizes vary by region. Kyoto (Kyōma) tatami are the largest at 191 cm × 95.5 cm; Tokyo (Edoma or Kantōma) tatami are smaller at 176 cm × 88 cm; and the smallest are Danchima mats at 170 cm × 85 cm used in public housing. These regional differences mean that a room described as '6 tatami' can vary in actual size depending on location.

Modern apartments often use a simplified definition where 1 tatami = 1.62 m² for listing purposes, regardless of regional variation. Always verify which definition a listing uses when precision matters.

Common Japanese Apartment Layouts and Their Sizes

Japanese apartments are categorized by their layout code, which describes the number of rooms and the presence of a living/dining/kitchen area. Understanding these codes alongside tsubo measurements helps set expectations when browsing listings.

A 1K (studio with kitchen) apartment typically ranges from 6 to 10 tsubo (20–33 m²). These compact units are popular among single professionals and students in major cities. A 1LDK (one bedroom plus living-dining-kitchen) typically measures 12 to 16 tsubo (40–53 m²). A 2LDK (two bedrooms plus LDK) usually falls between 18 and 22 tsubo (60–73 m²), and a 3LDK (three bedrooms plus LDK) commonly spans 25 to 35 tsubo (83–116 m²).

For single-family homes, 30 to 40 tsubo (99–132 m²) is considered a comfortable family size. Larger homes of 50 tsubo (165 m²) or more are common in suburban and rural areas. Land area in Japan is also frequently listed in tsubo, making this converter useful for evaluating plot sizes as well as building footprints.

Tsubo Pricing in Real Estate

Real estate prices in Japan are often quoted on a per-tsubo basis. The tsubo unit price (坪単価, tsubo tanka) allows for straightforward comparison between properties of different sizes. To calculate the tsubo unit price, divide the total property price by the area in tsubo.

For example, if a 25-tsubo apartment is priced at ¥37.5 million, the tsubo unit price is ¥1.5 million per tsubo. This metric is especially useful when comparing renovation costs, construction quotes, and land valuations across different regions of Japan.

Tokyo's central wards (Minato, Chiyoda, Shibuya) can command land prices exceeding ¥30 million per tsubo, while suburban and regional areas may range from ¥300,000 to ¥2 million per tsubo. Understanding this unit allows you to evaluate whether a listing is priced competitively for its location.

Using This Converter for Property Research

This tsubo converter is designed for two primary use cases: converting a tsubo measurement from a listing into square meters for easier comparison with international standards, and converting a known square meter area into tsubo to understand how it compares to Japanese norms.

The reference table included in this calculator shows typical apartment sizes in tsubo alongside their square meter equivalents, giving you immediate context when evaluating a listing. Clicking any reference size instantly populates the converter with that value.

Whether you are a foreign national relocating to Japan, an investor researching the Japanese property market, or a resident comparing apartments, understanding the tsubo unit will make navigating Japanese real estate listings significantly more intuitive.