Buying Diapers in Japan: Brands, Sizes and Where to Find Them

Disclosure: This article contains no affiliate links. Size ranges come from the official sites of Kao (Merries), Unicharm (Moony) and Daio Paper (GOO.N); store details come from Akachan Honpo and 7-Eleven; pool rules come from the City of Yokohama. Checked on October 10, 2026.

Dollar amounts are approximate at $1 ≈ ¥158 (October 2026). You pay in yen.

This guide is the cheat sheet: official manufacturer size charts with weight ranges converted from kilograms to pounds, the Japanese words printed on the packs, where to buy diapers in Tokyo, and what to know about swim diapers before you take a toddler to a pool.

Ramen Dad’s note: We bought diapers in Tokyo for years. Japanese brands are easy to find, and the size charts above help with the conversion.

Quick answer: how to buy diapers in Japan

Quick conversion: 1 kg = 2.2 lb. A 22 lb toddler is about 10 kg; a 30 lb toddler is about 13.6 kg.

How to buy diapers in three steps

1. Find your child’s weight in kilograms.
2. Look for テープ (tape) or パンツ (pull-on pants), then match the weight range (体重めやす) printed on the pack.
3. Check the count (枚) before you buy. If you’re trying a Japanese brand for the first time, start with a smaller pack when one is available.

Japanese diaper sizes, converted to pounds

Japanese diaper sizes go newborn, S, M, L, then “Big” (ビッグ) and “Bigger than Big” (ビッグより大きい). The ranges overlap, and each brand’s are slightly different, so check the pack. Pounds below are converted by me from the official kilogram ranges and rounded.

Merries (Kao): “Zutto Hada Sara Air Through”

Merries Air Through lineup (Japanese)

Moony (Unicharm)

Moony tape / Moonyman pants (Japanese)

Moony sells two tape lines: regular Moony (マシュマロ肌ごこちモレ安心) and the gentler 低刺激であんしん line. Both list the same newborn to M ranges above; the L tape size (9–14 kg) is listed for regular Moony. Moony 低刺激であんしん (Japanese)

Moony offers two M-size pull-on diapers: one for babies who are rolling over or crawling (labeled M 寝返り〜はいはい, 5–10 kg), and one for babies who are pulling up to stand (labeled Mたっち, 6–12 kg). Check both the weight range and your baby’s stage of movement. Moony has been renewing its products, so packaging on the shelf may vary.

Between sizes?

Kao says weight is only a guide: babies of the same weight can need different sizes depending on height, tummy and thigh size. Its signs that it’s time to size up include tight leg or waist bands that leave marks, more leaks, and a weight above the pack’s range. Kao’s size guide (Japanese)

My tip: don’t try to match a US “Size 3” to a Japanese “M.” Japanese makers don’t publish an official US conversion, so compare by weight instead. If you’re unsure, buy a small pack first.

Tape or pants? The words on the pack

Take a photo of this table so you can match words on the shelf.

If you can’t find what you need, show staff one of these on your phone:

Where to buy diapers in Tokyo

Akachan Honpo: the baby superstore

Akachan Honpo is Japan’s big baby-goods chain, with 130 stores in 39 prefectures (as of October 2025). Its company profile says it stocks diapers, bottles, strollers and carriers from as many makers as possible, carries many kinds of formula, and keeps aisles about 1.25 m wide where it can so strollers fit. Its online shop has separate categories for tape diapers, pants diapers and swim pants, which shows you what to look for in store. Akachan Honpo company profile (PDF) (Japanese)

Stores are often in shopping malls rather than on main streets, so check the location on its website before you set out.

Drugstores and supermarkets

Many Japanese drugstores (ドラッグストア) and supermarkets have a baby aisle with diapers, wipes and baby food. Look for the ベビー (baby) sign hanging above the aisle. Stock and brands vary by store, so if you need a particular size, it’s worth checking two shops.

To find one, search Google Maps for “drugstore” or “ドラッグストア” near your hotel, or “Akachan Honpo” / “アカチャンホンポ” for a wider selection. Check opening hours before you head out, especially after dinner.

Ramen Dad’s note: I’ve spent plenty of time in Tokyo drugstore diaper aisles. Look for the ベビー sign above the aisle.

Konbini: emergencies only

Convenience stores are open late, which makes them useful when you run out at 10 p.m. 7-Eleven lists Merries Pants, size L, 4 pack for ¥448.80 (≈$2.85) including tax, with sales regions listed for everywhere except Okinawa. But 7-Eleven also says listed products may not be carried by every store, may not be on sale even within those regions, and may have been discontinued; when I checked, the page also showed a notice that the product information can’t currently be displayed. Treat konbini as a backup, not your main plan. Only one size is listed, so if you need newborn or larger toddler sizes, a drugstore or baby store is a more reliable option. 7-Eleven product page (Japanese)

More on what konbini do and don’t sell for kids: my konbini food for kids guide.

Swim diapers in Japan: check the pool first

Japanese swim diapers are sold as 水あそびパンツ (“water-play pants”) or スイミングパンツ (“swimming pants”):

Two official cautions:

• Moony says swim diapers can’t completely stop urine or stool from leaking in the water, so they can’t prevent the spread of infection. The same page reminds parents that babies can drown in 10 cm (about 4 inches) of water and that you should never leave a child alone during water play. Moony swim pants (Japanese)
• Swim diapers are not regular diapers. Moony says its swim pants have no super-absorbent material, so they can’t be used as ordinary diapers. Change your child into a regular diaper after leaving the water.
• Pool rules differ. The City of Yokohama’s park pools ask that children who aren’t toilet-trained not use the pools, and they don’t allow swim diapers either, because water quality is hard to manage with many small children in the water. Other pools allow swim diapers. Yokohama City FAQ (Japanese)

So before you promise your toddler the hotel pool, ask the hotel or pool directly whether children in swim diapers can use it. My family rooms in Tokyo guide covers what else to ask when you book.

How many to pack before you shop

You don’t need to bring the whole trip’s supply. A practical plan:

1. Pack enough for the first one or two days, plus a few extra for flight delays, in your carry-on.
2. If your suitcases are being forwarded, keep diapers and wipes in your day bag (see the first-night bag list).
3. Buy a small pack in Japan on day one or two to test the fit, then buy more.

If you’re traveling by train, a big pack plus a stroller is a lot to carry, so buying smaller packs near each hotel can be easier.

Ramen Dad’s note: As a parent here, I have opinions on Japanese diapers. Buy a small pack on day one or two to test the fit, then buy more.

FAQ from parents

“Are Japanese diapers the same as US sizes?” Not exactly. Japanese packs use letters (S, M, L, Big) with kg ranges, and the makers don’t publish a US conversion. Compare your child’s weight with the range on the pack.

“My child is 25 lb. Which size?” 25 lb is about 11.3 kg. In Merries or Moony pants, that’s within the M (6–12 kg) and L (9–14 kg) ranges, so choose by fit: Kao says to size up if bands leave marks or leaks increase.

“Can I buy diapers at the airport or train station?” I didn’t find official confirmation for specific airport or station shops, so don’t rely on it. Bring enough for the first day, and plan a store stop.

“Do Japanese pools allow swim diapers?” It depends on the pool. Some allow them, and some, like Yokohama’s park pools, don’t allow children in any kind of diaper. Ask before you go.

“Where can I change a diaper?” Tokyo Metro says the accessible toilets at its stations have diaper-changing tables and baby seats (see my stroller or carrier guide). Some restaurant chains also list changing tables on their official pages; my eating-out guide covers which ones. On maps and floor guides, look for おむつ替え (diaper changing) or ベビールーム (baby room); a 授乳室 (nursing room) may or may not have a changing table, so check the sign.

“Where should I throw away used diapers?” Rules vary by facility, and I didn’t find one official rule for Tokyo. Use a diaper bin where one is provided. If there isn’t one, seal the diaper in a small bag and ask your hotel how to dispose of it, rather than leaving it in a public trash can.

Before you go: diaper checklist

1. Weigh your child and convert to kg (lb ÷ 2.2).
2. Screenshot the size tables above and the Japanese words on the pack.
3. Pack one or two days of diapers and wipes in your carry-on.
4. Find the nearest Akachan Honpo or drugstore to your hotel on a map.
5. Ask your hotel or pool whether swim diapers are allowed before packing them.
6. Keep a small emergency supply in the day bag; a konbini may or may not have your size.

For everything else about your child’s health on the trip, see my guide to what to do if your kid gets sick in Japan.

Ramen Dad’s note: If you remember one thing: pack enough for the first day or two, then buy near your hotel. You don’t need two weeks’ worth in your suitcase.

Size ranges, store details and pool rules checked on official Kao, Unicharm, Daio Paper, Akachan Honpo, 7-Eleven and City of Yokohama pages on October 10, 2026. Manufacturers change products and packaging, so always check the weight range printed on the pack.