What Size Clothes Do Newborns Wear? A Simple Guide for New Parents

If you’ve ever stood in front of a rail of baby clothes wondering what on earth "up to 1 month" actually means, you’re not alone. Between NB, 0-3 months, and weight-based sizing, it can all feel a bit... well, foggy.

So let’s clear things up. This guide explains how baby clothing sizes work, when to size up (or down), and how to choose the right outfits for your newborn. As always, we’ll keep it simple, supportive, and kind to your sleep-deprived brain.

Understanding Newborn Clothing Sizes

Let’s start with the basics.

• NB or "Newborn" typically fits babies up to around 7.5lbs (3.4kg)

• Up to 1 Month is often best for 7-10lb babies

• 0-3 Months suits babies from roughly 9 to 12lbs (4.1 - 5.4kg)

Each brand sizes differently, but these are general guidelines. Some babies skip NB sizes entirely. Others wear them for weeks.

At Lottie & Lysh, we offer sizing from Preemie through to 6 years, with soft fabrics and adjustable features (like fold-over mitts) that help your baby grow in comfort.

Looking for outfit inspiration? Explore our Newborn Baby Clothes collection

Weight-Based Baby Clothing Sizes

Weight is often more accurate than age when choosing baby clothes. Here’s a quick size chart to help:

Remember, every baby is unique. Some grow fast, others stay tiny for longer. If in doubt, size up. A slightly loose fit is far better than a too-tight one.

Shopping for a smaller arrival? View our Premature Baby Clothing

What Size Clothes Should I Buy for a Newborn?

If you’re buying clothes before baby arrives (or choosing a baby shower gift), here are some tips:

• For babies under 7.5lbs: Go with NB or "Newborn"

• For babies 7.5-9lbs: Try "Up to 1 Month"

• For bigger babies or longer wear: Choose 0-3 Months

Pro tip: Fold-over cuffs and stretchy seams help clothes fit for longer. Some of our Baby Grows & Rompers feature turndown ankle cuffs and fold-over mitts and if not, you can have add them added to any custom designed items!

Why Fabric & Fit Matter

Sensitive skin? Eczema? Heat rash? The right fabric makes a big difference. All Lottie & Lysh baby clothing is made from:

• OEKO-TEX or GOTS certified fabrics

• 95% cotton blends for softness and stretch

• Flat seams and breathable stitching

Our fits are loose, comfy, and baby-tested by real families. Nothing scratchy. Nothing stiff.

Learn more about our Ethical Baby Clothes

Dressing for the Season

A summer baby will need different layers than a winter one. Here’s what to keep in mind:

• Summer: Light layers, breathable rompers, sun hats

• Winter: Long sleeves, footed grows, cosy cardigans

Shop our seasonal Summer Baby Clothes collection

FAQs About Baby Clothing Sizes

What size is NB in baby clothes?
NB typically fits babies up to 7.5lbs or 3.4kg. It’s best for babies born on the smaller side or a little early.

Is NB the same as newborn?
Yes, NB means "newborn". Some brands use NB, others spell it out.

What are NB outfits?
NB outfits are clothing items designed specifically for newborn babies, often for babies weighing under 8lbs.

How do I know if clothes will fit my baby?
Check the brand’s size chart and consider your baby’s weight and age. Look for flexible fabrics and adjustable cuffs.

Do handmade baby clothes fit differently?
Yes. Handmade baby clothes (like ours) often have softer seams and better stretch, offering more comfort and a longer-lasting fit.

Shop with Confidence

Whether you’re prepping for your own little one or choosing a gift, we hope this guide made things feel a little clearer. If you’re still not sure which size to choose, feel free to send us a message — we’re always happy to help.

Ready to find the perfect NB outfit? Our Newborn Baby Clothes collection is full of beautifully handmade, skin-kind styles from 0-6 years.

Related Links:

• Swaddle Blankets

• Baby Grows & Rompers

• Should You Wash New Baby Clothes?