How to Choose the Right Size Bento Box

When shopping for a bento box, one of the most common questions we hear is:“How big should it be?”

With so many sizes and shapes available, it's easy to feel overwhelmed. But choosing the right bento box size is key to packing meals that are satisfying, balanced, and suited to your lifestyle.

In this post, we’ll break down everything you need to know—from calories and food volume to activity levels and packing style—so you can confidently pick the size that’s just right for you (or your family).

Our Kokeshi Bento Maneki Neko comes in 2 sizes (640ml and big, 1,200ml), and can both hold a good sized lunch depending on your needs.

The Bento Box Size Rule of Thumb: 1ml = 1kcal

This simple rule is widely used in Japan: 1 milliliter ≈ 1 kilocalorie. So, if your ideal lunch is around 600 kcal, a 600 ml bento box is probably perfect. Here's a quick overview:

User Profile	Box Volume (ml)	Example Meal Size
Young child (3–6 yrs)	280–400 ml	Small rice ball, veggies, fruit
Elementary school child	400–600 ml	Child-sized lunch with variety
Adult (sedentary)	600–800 ml	Balanced light lunch
Adult (active) / Teen	800–1,200 ml	Hearty lunch, extra energy needed
Meal prep or picnic	1,200 ml+	Multiple courses or shared meals

Not sure how many calories you typically eat for lunch? Try using a calorie calculator and track your food for a day or two to get a rough idea, or see a nutritionist/dietician to get a better evaluation.

Consider Your Activity Level

The more active you are, the more fuel your body needs. If you have a sedentary lifestyle, opt for a compact bento box (600-700ml). If you're an athlete, a teen or a manual worker that moves a lot daily, go bigger: anything from 800ml to 1,200ml is recommended.

Are you on a weight loss journey? Bento boxes can help with portion control if you choose a smaller one! Once you know your daily rough caloric intake, divide it by 3 or 4 to know how much you typically eat for lunch, then subtract 100-200 kcal from that.

For an average adult with a daily intake around 2,000 kcal, that would mean choosing a box somewhere between 500 to 700ml, depending on how many times you like to eat in a day. A smaller bento box helps you feel full while avoiding oversized portions.

Our Kokeshi Bento Kyoto Geiko, while being smaller than other popular models, can actually pack a fair amount of food thanks to its dome lid. This particular bento packed 130g of rice as well as a small chicken cordon bleu and lentil patties for a diet friendly but filling lunch.

Bento Packing Proficiency: Are You a Beginner?

A well-packed bento should be tightly filled—this keeps food from shifting and helps with portion control. But if you're just starting out, packing tightly can be tricky.

For beginners, a slightly larger box (700–900 ml) gives you breathing room and makes packing easier. Experienced bento makers can downsize and still fit a full meal thanks to clever arrangement.

Think of it like a suitcase: the better you pack, the more you can fit. But when you're new to bento, it's OK to have extra room as you learn.

Our Blue Ocean Big Bento Nami is great for beginners as it is large enough for pasta and salad, but can also be used with silicone cups to organize your sides easily.

What Kinds of Foods Are You Packing?

The types of food you like can also impact the size you need, so you should also take that into consideration.

• Salads, fruits, and sandwiches tend to take up more space as they’re bulkier and less dense.
• Onigiri, curry, and stir-fries pack tightly and need less room.
• Kids’ lunches might include a juice box or yogurt pouch inside the bento box to avoid crushed snacks in backpacks.

If your food is easy to pack in a bigger container, look for a roomier box or a two-tier design like the Nokorimono Bento Box, which gives you flexibility in how you organize space.

Want to See Real-Life Examples?

Not sure how big a 600 ml box really is—or how much food it fits? Check out our YouTube playlist with real packing examples of our most popular boxes:

"Pack Lunch With Us!" Bento Box Size Guide Series

You'll see how much food different bento boxes hold, plus tips for packing them beautifully and efficiently.

Still Not Sure? Here Are Some Bento Boxes Recommendations from our Team!