New Trip Editorial Department　　Updated: 2026.05.28

The Complete Guide to Choosing the Right Suitcase Size: Detailed Explanation of Stays, Carry-on, and International Flights

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"Which is better, S size or M size?"
"I don't know what size I can bring as carry-on."
"How many liters do I need for an overseas trip?"

The most common mistake when choosing a suitcase is size selection.

In fact, the New Trip editorial department has received numerous inquiries such as:

  • I couldn't fit as much luggage as I thought.
  • It was too big and difficult to move around.
  • I was charged extra by an LCC.

Especially recently, with the increase in LCC use and demand for short trips, the importance of choosing a "size that suits you" has become higher than before.

This article clearly explains how to choose a suitcase size that won't lead to regrets, based on travel duration, purpose, and airline.

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Table of Contents

1. Suitcase Size Guide

2. How to Measure Luggage Size

3. Carry-on Suitcase Size Standards

4. Choosing the Right Suitcase Size for International Flights

5. By Use Case | Recommended Sizes & Models

VI. Frequently Asked Questions (FAQ)

7. Summary

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一、スーツケースのサイズ目安一覧

First, let's check the most helpful "Size Guide by Number of Nights."

容量目安 泊数目安 おすすめ用途
20〜35L 1〜2泊 出張・国内旅行
35〜45L 2〜4泊 短期旅行・機内持ち込み
50〜70L 5〜7泊 国内長期旅行・海外旅行
70〜100L 1週間以上 留学・長期滞在

However, even for the same 2-night, 3-day trip, the optimal size varies depending on the amount of luggage.

ワンサイズ上がおすすめな人

  • Frequent winter trips
  • Lots of cosmetics and gadgets
  • Buy a lot of souvenirs
  • Want to pack children's luggage too

コンパクトでも十分な人

  • Minimalist
  • Plans to do laundry
  • Frequently uses LCCs
  • Wants to reduce luggage
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💡 Even within the New Trip editorial department, more people are recently choosing "slightly smaller" items. This is because travel styles that prioritize ease of movement are becoming more common.

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二、スーツケース サイズの測り方

Surprisingly common are cases where people
misjudge the size of their luggage.

Especially with LCCs, even being a few centimeters over can result in additional charges.

スーツケースサイズは「3辺合計」で決まる

Generally, it is determined by the total size of these three sides:

  • Length
  • Width
  • Depth

For example, for a size of

55cm × 35cm × 25cm

the sum would be

55 + 35 + 25 = 115cm

which falls within the carry-on baggage standards.

測定時の注意点

When measuring the size, you need to include:

  • casters
  • handles
  • side parts

If you only measure the main body, it's not uncommon for the actual size to exceed the limit.

容量（L）だけで判断しない

Even with the same 40L capacity, storage capacity can vary greatly depending on:

  • Front opening
  • Interior design
  • Expansion features

Instead of thinking, "It's 40L, so I'm safe," it's important to check the actual external dimensions.

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三、機内持ち込みスーツケースのサイズ基準

The most popular size recently is the "carry-on compatible size."

Since you don't need to check it in, it offers the following benefits:

  • No waiting at the airport
  • Lower risk of lost luggage
  • Significantly easier to get around

一般的な機内持ち込みサイズ

For most airlines,

  • the sum of the three dimensions must be within 115cm
  • the weight must be within 7-10kg

These are the general standards.

In terms of capacity,
35-40L is a convenient size.

LCC利用時は特に注意

With LCCs,

  • Up to 7kg
  • Only one piece of luggage
  • Measured including wheels

such restrictions can be quite strict.

Therefore, it is important to choose:

  • Lightweight models
  • Compact designs
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💡 New Trip Editorial Memo: When using carry-on size luggage for 2-3 day trips, the three features I find most convenient are the front-opening compartment, caster stopper, and expansion function.

📚Related Article:『Complete Guide to Carry-On Suitcases | How to Choose One That Won't Fail You with 115cm/7kg Limits and LCCs』

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四、国際線で失敗しないスーツケースのサイズ選び

When traveling internationally, choosing the right size is even more crucial than for domestic travel.

A particularly important one to be aware of is the "158 cm rule."

国際線の158cmルールとは？

For many airlines,

"Length + Width + Depth = within 158cm"

is the checked baggage standard.

When choosing a large size, it's necessary to check that it does not exceed this standard.

海外旅行のサイズ目安

旅行日数 容量目安
3〜5日 40〜60L
5〜7日 60〜80L
1週間以上 80L以上

When traveling abroad, it's recommended to choose items while keeping in mind space for souvenirs on your return trip.

海外旅行では耐久性も重要

In addition to size, the following are also important:

  • Caster performance
  • Body strength
  • TSA lock
  • Security

Especially on European cobblestones, you can really appreciate the comfort of quiet double casters.

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📚Related article: "International Flight Suitcase Size Guide: How to Choose Carry-On and Checked Luggage"

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五、用途別｜おすすめサイズ＆おすすめモデル

1〜3泊なら「Sサイズのスーツケース」

Recommended for:

  • Those who want to carry their luggage on board
  • Frequent business travelers
  • Frequent Shinkansen users
  • Those who want to pack light

Especially recently,
with the increase in LCC usage and demand for short trips,
"lightweight + carry-on compatible" has become a very important factor.

・Recommended model: New Trip 0702Plus

  • Coin locker compatible
  • Front opening
  • Carry-on compatible
  • Excellent for LCC use

This is a versatile model that can easily be called the "go-to" choice.

New Trip 0702Plus スーツケース

USBポート付き・機内持ち込みモデル

New Trip 0702Plus

Sサイズ・42L｜外寸54*35*24cm｜3.8kg

フロントオープン ABS+PC素材 USB充電ポート ストッパー付き TSA008ロック

¥21,980

商品を見る

3〜5泊なら「Mサイズのスーツケース」

Recommended for:

  • Those who want to use it both domestically and internationally
  • Those who have a slightly larger amount of luggage
  • Those who want to use one unit for a long time

The most versatile size is M.

It's a size that is unlikely to be a mistake even for first-time suitcase buyers.

・Recommended Model: New Trip 2011

  • Large capacity storage space
  • Smoother with five-wheel design
  • With stopper
  • TSA lock

With a good balance of "capacity, mobility, and ease of use,"
this versatile model is easy to use for a wide range of trips, from domestic to international.

New Trip 0211 スーツケース

5輪設計・スクエアデザインモデル

New Trip 0211

Mサイズ・68L｜外寸64*40*30cm｜4kg

スクエアデザイン ABS+PC素材 5輪設計 ストッパー付き 物掛けフック付き

¥24,580

商品を見る

③Lサイズ｜New Trip 0201

For trips of one week or more, choose "L Size".

Recommended for:

  • Overseas travel
  • Study abroad
  • Winter travel
  • Family trips

If storage capacity is a priority, the L size is recommended.

・Recommended model: New Trip 2011

  • Ultra lightweight
  • Expandable
  • TSA lock
  • YKK zipper

It can be said that if "cost performance is important," choosing this one is a sure bet.

New Trip 0201 スーツケース

拡張機能付き・超軽量モデル

New Trip 0201

Lサイズ・95L(拡張後109)｜外寸75*48*28cm｜4.4kg

超軽量 ABS+PC素材 拡張機能付き TSAロック

¥17,980

商品を見る
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六、よくある質問（FAQ）

Q1. スーツケースのサイズ目安はどう決めればいいですか？

A1：基本は泊数で選びます。ただし、季節・荷物量・お土産量によって最適サイズは変わります。迷った場合は少し余裕のあるサイズがおすすめです。

Q2. 機内持ち込みできるサイズは何Lですか？

A2：一般的には35〜40L前後が目安です。ただし、航空会社によって規定が異なるため事前確認が必要です。

Q3. MサイズとLサイズ、どちらがおすすめですか？

A3：迷った場合はMサイズがおすすめです。国内・海外どちらにも対応しやすく、もっとも使いやすいサイズです。

Q4. 国際線では大型サイズでも大丈夫ですか？

A4：多くの航空会社では3辺合計158cm以内が基準です。超える場合は追加料金が発生する可能性があります。

Q5. 軽量モデルを選ぶメリットは？

A5：荷物を多く入れやすく、移動負担も軽減できます。特にLCC利用では大きなメリットがあります。

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七、まとめ

When choosing a suitcase, it's important to consider not just its "size,"

but also whether it "suits your travel style."

  • For short trips, a carry-on size
  • For versatility, an M size
  • For long trips, an L size

By choosing a suitcase that matches your needs, your travel comfort will greatly improve.

As the New Trip editorial team, we also feel that the following are extremely important when actually using a suitcase:

  • Ease of movement
  • Ease of storage
  • Low stress

We hope you find the perfect suitcase for you and enjoy a comfortable trip.

執筆・監修

New Trip編集部
本記事は、スーツケース・旅行用品ブランド「New Trip」の編集部により制作されました。
製品開発やユーザーの声を活かしながら、ユーザーに合ったスーツケースや、旅行・出張をより快適にするアイテムを発信しています。

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