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Posted on Mar 7, 2007 in Parent Hacks, Tips, Tutorial or How-to | 75 comments

Guide to choosing the right size bento box


So you ordered a bento box online, it arrives and you’re shocked at how tiny it is. People try to tell you to just eat less, but you have a sneaking suspicion that you may have accidentally bought a bento box sized for a 2-year-old instead of an adult. Here’s how to tell: check the box’s total capacity against the gender/age/height guidelines in the table below (I translated them from a popular Japanese website that’s been getting a lot of media exposure in Japan — they’re based on official Japanese nutritional guidelines).

In Japan, bento box size is described not by its dimensions (inches or centimeters), but instead by its volume or capacity (in milliliters — ml). Why? Because a rule of thumb in Japan is that when you pack a bento box normally (A: 3 parts grain dishes, 1 part protein dishes, 2 parts vegetable dishes; B: without candy, junk food or fatty food; and C: without empty space), calories correspond directly to capacity. So a 600ml box should hold a 600-calorie meal.

Capacity is usually written on the bento box package and also often on the bottom of the bento box in raised plastic. If you’re not sure of your box’s capacity, you can measure it yourself by filling the box with water, pouring the water into a liquid measuring cup and checking the milliliters (ml) or ccs there. Most, if not all, Japanese eBay sellers should be able to tell you the size of a box in ml if asked. (Edited to add: 240ml = 1 cup American)

Here’s a quick height conversion chart in case you don’t know your height in centimeters.

Age (Women) Avg. height (in cm) Calories per meal (kCal) Bento Box Size (in ml)
3-5 85-110 450 400
6-8 116-128 500-550 500
9-11 134-147 600-650 600
12-14 155 770 700
15-17 157 735 700
18-20′s 158 685 600
30′s 157 670 600
40′s 157 670 600
50′s 152 650 600
60′s 152 650 600
70′s 147 520 500
80′s 147 520 500

* Source:

Age (Men) Avg. height (in cm) Calories per meal (kcal)
Bento Box Size (in ml)
3-5 85-110 450 400
6-8 117-128 500-550 500
9-11 133-145 600-650 600
12-14 160 885 900
15-17 170 920 900
18-20′s 171 885 900
30′s 170 885 900
40′s 170 885 900
50′s 165 800 800
60′s 165 800 800
70′s 160 620 600
80′s 160 620 600

* Source:

Step 2: Adjust for your level of physical activity and height *

Physical activity:
Level 1: Low (spend most of your time sitting or quiet)
Level 2: Moderate
Level 3: High (lots of exercise, sports, etc.)

Adjust the size of the bento box for your height and physical activity:

Add 100ml to your bento box size for:

  • Taller than average height
  • High physical activity (Level 3)

Subtract 100ml from your bento box size for:

  • Shorter than average height
  • Low physical activity (Level 1)

* Source:

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I’m not sure how much to adjust if, for example, you’re both taller than average and have high physical activity (add 100ml or 200ml?), but it’s something to start with. If you’re dieting, you might want to choose a smaller box, but these are the general Japanese guidelines for packing dense food (i.e. rice or pasta, veggies and a protein). Bulky foods like sandwiches or salads would require larger boxes than the chart above.

The Japanese Food Guide Spinning Top defines the following food groups:

Category Cooking Category (Ideal Japanese Bento Makeup)
Grain dishes Dishes that mainly include rice, bread, noodles and pasta (carbohydrate sources) 3 parts
Vegetable dishes Dishes that mainly include vegetables, potatoes, beans (excl. soy beans), mushrooms and seaweeds (various vitamins, minerals and fiber sources) 2 parts
Fish and Meat dishes Dishes mainly include meat, fish, eggs, soy beans and soybean products (protein sources) 1 part
Milk Milk, yogurt and cheese (calcium sources) (occasional)
Fruits Fruits and fruit-like vegetables (Vitamin C and potassium sources) (occasional)