A Beginner’s Guide to Japanese Tatami Sizes and Room Names

If you’ve ever browsed a Japanese real estate listing, you’ve likely seen unfamiliar room labels like “8畳和室” or “6J.” These aren’t typos or codes—they’re references to the number of tatami mats in a room. In Japan, room sizes are traditionally measured by the number of tatami mats that fit on the floor, and room names often reflect the material, layout, and purpose of the space.

For foreign buyers, understanding how these measurements and labels work is essential. Whether you’re exploring akiya listings or planning a renovation, this guide will help you read Japanese floor plans with confidence.

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What Is a Tatami Mat?

Tatami mats are traditional Japanese flooring materials made of woven straw and usually bordered with cloth. Historically used in everything from samurai residences to tea ceremony rooms, they remain a core feature of older homes and are still common in rural properties and akiya.

A standard tatami mat is rectangular and roughly:

• 91 cm x 182 cm (about 3 ft x 6 ft) in the Kyoto standard
• 85 cm x 179 cm in the Nagoya standard
• 88 cm x 176 cm in the Tokyo (Kanto) standard

The slight variation in sizes across regions means an “8-tatami room” in Kyoto might be a little larger than one in Tokyo.

How to Read Room Sizes in Tatami (畳 / 畳数 / Jō)

In Japanese listings, you’ll often see room sizes noted like this:

• 6畳 (roku-jō) = 6 tatami mats
• 8畳和室 (hachi-jō washitsu) = 8-tatami traditional room
• 4.5J = 4.5-tatami room (often abbreviated with a “J” in English-style listings)

You might also see:

• 和室 (washitsu) = Japanese-style room with tatami
• 洋室 (yōshitsu) = Western-style room (wood or tile flooring)
• LDK = Living, Dining, Kitchen combo

Rooms that measure 4.5, 6, or 8 tatami mats are common in older homes, especially in rural Japan.

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Why Are Room Sizes Measured This Way?

Tatami were traditionally used as both flooring and units of measurement. Since they’re modular, they allowed builders to design spaces that could be easily understood and rearranged. Even modern homes sometimes retain this measurement style for consistency and cultural preservation.

For example:

• A 6畳 room is ideal for a small bedroom or guest room
• A 4.5畳 room might be used as a study or tea room
• An 8畳 room is large enough for a sitting room or multi-use space

Knowing this helps you visualize how large each space is and whether it will meet your needs for sleeping, storage, or furniture.

Common Room Terms You’ll See in Listings

Here’s a quick glossary of common room names and labels:

• 和室 (Washitsu): Japanese-style room with tatami flooring
• 洋室 (Yōshitsu): Western-style room with hardwood or modern flooring
• LDK: Combined living, dining, and kitchen area (e.g., 3LDK = 3 rooms + LDK)
• 玄関 (Genkan): Entryway
• 押入れ (Oshiire): Traditional built-in closet
• 縁側 (Engawa): Wooden-floored corridor/veranda next to garden-facing room
• 床の間 (Tokonoma): Decorative alcove for art or flower arrangement
• 風呂 (Furo): Bathing room
• トイレ (Toire): Toilet room (often separate from the bath)

‍How Old Houses Japan Helps

At Old Houses Japan, we help international buyers understand these traditional layouts, especially when looking at rural or historic properties. Many akiya homes still use tatami mat sizing in their listing descriptions, so we:

• Translate and explain floor plans in plain English
• Help assess whether spaces fit modern living needs
• Recommend layout ideas or renovations if you want to convert tatami rooms into other types of spaces

Final Thoughts

Tatami mat sizing is a unique and beautiful part of Japanese architecture—but it can be confusing at first. Understanding how to interpret these measurements and room types gives you a real advantage when evaluating homes, whether you're browsing listings or preparing to renovate.

Want help interpreting a floor plan or finding a traditional home with the perfect washitsu? Visit Old Houses Japan to explore listings and get expert guidance.