A Sizing Guide for All Brands

With so many brands from so many different places, each with their own system for determining size—it can make choosing the “correct” size difficult when listing. To help, I’ve outlined how sizing works and what you would want to list it under for maximum exposure.

HINT: Always make sure to take a pic of the size tag and/or list the actual size in the description. This includes shoes, especially ones that use Euro sizing.


0-3 MONTHS AND 3 MONTHS:  These are the same.

3-6 MONTHS AND 6 MONTHS:  These are the same. Size 6 month means it fits UP TO 6 months. So list both of these sizes in the 3-6 month size category.

6-12 MONTHS AND 12 MONTHS:  These are the same.

9 MONTHS:  This is its own thing. List it as 6-12 months AND include the specific size in the listing title.

12-18 MONTHS AND 18 MONTHS:  These are the same.

18-24 MONTHS AND 24 MONTHS:These are the same.

24 MONTHS AND 2T:  These are different; typically 2T is larger.

I have seen a number of brands that use centimeter sizing or a larger age range (such as 2-4 years) listed in Kidizen under the “One Size” label. I would advise against this because it limits the number of people who see your item. Many buyers use their specific kids’ size filter to search for items and it’s unclear how many have “One Size” chosen as an option. Instead, list it based on how you think it fits.

Example: For a Mini Rodini Dress with size 116/122 on the label (they consider that to be a size 5-7) that fits like my daughter’s size 6 dresses, I would list it as a 6. While listing, I would include a photo of the tag, as well as add a message in the description that said something like: “Size 116/122, which is a 5-7. Fits best as a 6 to me.” As long as you have the actual size somewhere—you are good to go, in my opinion!

HINT: The Hanna Andersson brand now puts the U.S. size along with their centimeter size on the tag, which has been incredibly helpful. Just note it is a little different from other brands that use centimeters.

Regardless, every brand’s sizes seem to run differently. The best thing to do is to do a quick search for their size chart if you are unsure on sizing and conversions. And of course, providing measurements in your listing will always be the safest bet for any questions that may come up.

Happy Sizing!


Randi Pivec a.k.a. Violet’s Closet, is a kids clothes shopaholic and Wonder Woman-obsessed mama of two who is just trying to figure this parenting thing out. She loves to answer any and all questions about Kidizen in the app and the Hello Kidizen Facebook group. When she isn’t helping other moms navigate buying and selling, she’s curating collections and brainstorming new style features.