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What Is the Best Size for a Children’s Room? Floor Plan Tips to Get It Right

How many tatami mats should a children’s room have? Using 6 tatami mats as a baseline, this article explains how to choose the right room size and layout based on family structure, gender, and future partitioning plans.

Last updated: About 2 min read

Many people planning to build a home struggle with how to design the children’s room. The room size in particular needs to be considered in light of the overall house size, the number of children, and their future growth. In this article, we explain the average size of a children’s room, how to think about the best size, and the key points for creating a floor plan that avoids common mistakes.

What is the average size of a children’s room?

Six tatami mats is the standard benchmark

The standard size for a children’s room is 6 tatami mats, which provides enough space even with a bed, study desk, and wardrobe in place.Other common sizes are 4.5 tatami mats, 5 tatami mats, 5.5 tatami mats, and 8 tatami mats. A 4.5-tatami room can feel cramped, while an 8-tatami room may be larger than necessary in some cases.

Also consider the children’s gender and age

If siblings are of different genders or there is a significant age gap, separate rooms are ideal.If they are the same gender and close in age, they may share a larger room. It is reassuring to choose a design that also anticipates adding a partition in the future.

What size is best for a children’s room?

Make a comprehensive judgment based on house size and family size

The average children’s room is 6 tatami mats, but balance with the overall size of the house is important. If the home is around 30 tsubo, 4.5 tatami mats is a useful guide; if it is around 35 tsubo, 6 tatami mats is the benchmark.

If you choose a larger room, also plan for future partitioning

Planning to divide a 9-tatami room into two rooms later can also be effective. Costs and flexibility vary depending on the partition method, such as wall construction, fittings, or shelf-and-curtain dividers.A design that takes outlet and window placement into account is important.

Even a small room can feel spacious with the right ideas

By using ideas such as separate storage space, a loft bed, low-profile furniture, and white-toned wallpaper, you can create a comfortable space even in a 4.5-tatami room.

What are the key points for a floor plan that avoids mistakes?

Give children a private space as well

By the upper elementary school years through high school, having a space of their own becomes important for children’s emotional stability and growth.Rather than focusing only on square footage, aim for a design that gives them a clear sense of “having their own place.”

Listen to the children’s opinions too

If the children are old enough, asking what they want in their room helps create a stronger sense of attachment. When the views of the people who will actually use the room are reflected in the design, the result is a room that is easier to live with.

Frequently Asked Questions (FAQ)

Q. What is the minimum size that is sufficient for a children’s room?

A minimum of 4.5 tatami mats is enough to place the basic furniture. However, this assumes that storage space is secured separately.

Q. How can a children’s room be used after the children move out?

More people are using it as a study, hobby room, or home office. It is useful to plan for future repurposing in advance, such as outlet placement and natural lighting.

Q. How much does it cost to add a partition later?

If you divide the room fully with wall construction, a rough guide is around JPY 200,000 to JPY 500,000. If you use a simpler partition with fittings or shelving, it may be possible from tens of thousands of yen.

Q. Is there an ideal window position for a children’s room?

A south-to-east-facing orientation is ideal for securing natural light and ventilation. For privacy protection, it is also important to design the room so the window does not directly face a neighboring home’s window.

Daisuke Inazawa, President & CEO of INA&Associates Inc.

Author

President & CEOINA&Associates Inc.

President & CEO of INA&Associates Inc. Leads real estate brokerage, rental leasing, and property management across Greater Tokyo and the Kansai region. Specialises in income-property investment strategy and advisory for ultra-high-net-worth individuals.

Daisuke Inazawa is the President and CEO of INA&Associates Inc., a Japanese real estate firm headquartered in Osaka with a Tokyo branch. He leads the company's three core businesses — real estate sales brokerage, rental leasing, and property management — across the Greater Tokyo Area and the Kansai region.

His areas of expertise include investment strategy for income-generating real estate, profitability optimisation of rental operations, real estate advisory for ultra-high-net-worth individuals (UHNWIs) and institutional investors, and cross-border real estate investment. He provides data-driven, long-horizon advisory to investors in Japan and overseas.

Under the management philosophy "a company's most important asset is its people," he positions INA&Associates as a "people-investment company" and is committed to sustainable corporate-value creation through talent development. He also writes and speaks publicly on leadership and organisational culture in times of change.

He has passed eleven Japanese professional qualification examinations: Licensed Real Estate Broker (Takken), Certified Real Estate Consulting Master, Licensed Condominium Manager, Licensed Building Management Supervisor, Certified Rental Housing Management Professional, Gyōseishoshi Lawyer (administrative scrivener), Certified Personal Information Protection Officer, Class-A Fire Prevention Manager, Certified Auctioned Real Estate Specialist, Certified Condominium Maintenance Engineer, and Licensed Moneylending Operations Supervisor.

  • Licensed Real Estate Broker (Takken)
  • Certified Real Estate Consulting Master
  • Licensed Condominium Manager
  • Licensed Building Management Supervisor
  • Certified Rental Housing Management Professional
  • Gyōseishoshi Lawyer (Administrative Scrivener)
  • Certified Personal Information Protection Officer
  • Class-A Fire Prevention Manager
  • Certified Auctioned Real Estate Specialist
  • Certified Condominium Maintenance Engineer
  • Licensed Moneylending Operations Supervisor