What Size Should I Buy for My Newborn? A Guide to European Baby Sizing

Shopping for a newborn before they arrive comes with one surprisingly difficult question:

What size should I actually buy?

Newborn, 0M, 1M, 3M- and then add European sizing into the mix, and it can quickly become confusing.

As a mother of five and after years of helping families choose going-home outfits and newborn clothing at El Rincon de Maria, I’ve learned that the number on the label only tells you part of the story.

For those very first outfits, your baby's expected birth weight is often much more helpful than their age.

Newborn Sizing: Where Should You Start?

As a general guide, we recommend:

Size	Approximate Fit
Preemie	Under approximately 6 lbs
0M / Newborn	Approximately 6–7 lbs
1M	Approximately 7–9 lbs
3M	Approximately 1–3 months
6M	Approximately 3–6 months

These are guidelines rather than guarantees. Every baby is different, and just like adult clothing, every baby brand fits a little differently.

That is especially important when shopping European brands.

Should I Buy 0M or 1M for the Hospital?

This is probably the question we receive most often.

If your baby is expected to be around 6–7 lbs, we generally recommend 0M or newborn for their first outfit.

If your baby is expected to be closer to 8–9 lbs, we usually recommend 1M.

If your doctor expects a particularly small baby or your baby will arrive prematurely, look for preemie sizing rather than trying to make a larger newborn outfit work.

For the going-home outfit specifically, we prefer a proper newborn fit rather than buying significantly larger with the idea that baby will "grow into it."

This is one of the most photographed outfits of those first days. You want your baby to look comfortable and cozy rather than lost inside their clothes.

European Baby Clothes Tend to Fit Differently

If you're used to American baby sizing, European newborn clothing may initially feel different.

European baby clothing is often designed for a closer, more tailored fit, particularly traditional knitwear, two-piece sets, footed sets and special-occasion clothing.

You may also see sizes such as:

0M • 1M • 3M • 6M

rather than the broader ranges commonly used by American brands.

This can actually make choosing a going-home outfit easier once you understand the sizing because you can select something much closer to your baby's expected size.

The Brand Matters

One of the most important things we've learned after years of carrying European baby clothing is that you cannot assume every brand fits exactly the same.

Some brands run smaller, some are closer to true to size, and certain styles within a collection can fit differently.

For example, brands such as Paz Rodríguez, Foque and Mac Ilusión tend to fit smaller, while other newborn brands may fit closer to traditional sizing.

This is why we always recommend checking the sizing information on the individual product and reaching out to us if you're between two sizes.

We work with these collections every day and are always happy to help you choose.

What If I Don't Know How Much My Baby Will Weigh?

Don't worry... most of us don't!

Your doctor may be able to give you an estimated birth weight as you get closer to your due date, although even those estimates aren't exact.

If you are shopping earlier in your pregnancy and have absolutely no idea, 1M usually gives you a little more flexibility.

For the hospital bag, however, we like having at least one smaller option available.

A practical approach is to pack:

one 0M/Newborn outfit + one 1M outfit

That way, you have options once baby arrives.

Should I Skip Newborn Size and Just Buy 3M?

For those first outfits, we wouldn't.

It can be tempting to think that buying larger means you'll get more use out of an outfit, but a 3M garment can be quite large on a brand-new baby.

For everyday basics, having larger sizes ready is wonderful.

But for a going-home outfit, first photos, meeting grandparents or those first special days at home, we recommend choosing something intended to fit your baby now.

There will be plenty of time for the bigger sizes.

How Much Newborn Clothing Do I Actually Need?

You don't need an enormous newborn wardrobe.

Babies grow quickly, and some babies move through their smallest sizes faster than others.

Instead of buying dozens of outfits in one size, we prefer building a thoughtful newborn wardrobe with a few pieces you truly love:

Several comfortable everyday basics
2–3 pajamas
A few soft knit sets
One special going-home outfit
A cardigan or extra layer depending on the season
Bonnets, socks and other small essentials
A soft blanket for the hospital, stroller and first days at home

Then add larger sizes as your baby grows.

Choosing a Special Newborn Outfit

There is something different about shopping for those first pieces.

They become the outfits in the photographs you keep forever. Sometimes they are folded into a memory box. Sometimes they're passed down to a younger sibling.

For these pieces, I always recommend choosing something that feels timeless rather than trendy.

Soft ivory, white, baby blue, blush pink, pale yellow and beautiful neutrals photograph wonderfully and never really date.

Traditional details such as fine knitwork, delicate collars, hand-finished details, bonnets and matching blankets make these pieces feel particularly special.

Our Newborn Luxury Collection was curated with exactly these moments in mind: beautiful European pieces for going home, first photographs, gifting and those precious first weeks.

What Size Should I Buy as a Newborn Gift?

If you're buying for someone else's baby and don't know the expected birth weight, 1M or 3M is usually more practical than the smallest newborn size.

Parents often choose the going-home outfit themselves, so for gifts we also love pieces that don't depend quite as much on exact sizing.

A beautiful blanket, personalized name blanket, cardigan, nursery accessory or gift card can be especially thoughtful.

Our Best Newborn Sizing Advice

If you remember only one thing, remember this:

Shop for the baby you expect to have, not the baby six months from now.

For those first special outfits, a beautiful fit matters.

Use expected birth weight as your starting point, check the fit notes for the individual brand, and don't hesitate to ask for help.

We have dressed thousands of babies at El Rincón de María, and helping a mother choose that tiny first outfit never gets old.

Because you may only bring your baby home for the first time once — but you'll look at those photographs forever.

Need Help Choosing a Size?

Send us your baby's expected weight, due date and the outfit you're considering, and we'll be happy to help you choose the size we think will work best.

Our store's email: info@shopelrincondemaria.com

About the Author

Ani Certain is the founder and creative director of El Rincón de María, an online boutique dedicated to timeless European children's clothing. A mother of five, Ani curates each collection with real life, comfort and meaningful childhood moments in mind.