Baby clothes sizes, birth to 3

Go by your baby's length and weight. The age on the label is a rough hint. Mother & Baby's guide says the size on a label is usually the maximum, so "6 months" means up to 6 months. Sizes vary by maker, and a child can be different sizes in different shops.

A size chart from two makers

These are the charts Kite and Mamas & Papas publish, read on 3 November 2026. Both figures are the baby's body measurements, as the makers give them. Check the chart of the shop you're buying from before you trust any of these.

Kite gives no weight above 3-6 months, and Mamas & Papas gives none for 2-3 years. We won't fill those gaps with a guess.

Why shops disagree

Take the word "newborn". Kite and Mamas & Papas both say 50 cm. Pepa London lists 42 to 46 cm and 3 kg. Trotters says 50 to 56 cm. Same word, up to 14 cm apart.

M&S goes further. Its sleepsuit page runs Early, Tiny, Newborn, 1 Month, then 0-3 Months and up to 2-3 Years, so there are four labels before you even reach 0-3 months. We didn't find M&S's own measurements for them. Both M&S multipacks are sold from 5 lbs.

Your own baby's numbers settle it. Measure before you buy online from a shop you don't know.

What to buy first

Mother & Baby suggests that bigger babies may be a tight fit in newborn size, and that a baby might not fit it for long anyway. It suggests 0-3 months instead, up to about 13 to 14 lb, roughly 6 kg. That's reasonable. You can always roll a cuff.

Early and Tiny sizes are fine to skip unless your baby comes early or small. If they do, they're easy to pick up afterwards.

Three catalog packs show the range, all checked 3 November 2026:

M&S states 100% cotton and a 40°C wash on both of its packs. Its sleepsuits have poppers, and it says the scratch mitts run up to size 3-6 months. The Morrisons page for Nutmeg's bodysuits doesn't state the fabric. There are more options under clothes in the catalog.

Sleepsuits bring up sleep, and a size label changes nothing there. The NHS says babies can overheat from too much clothing or bedding, and suggests a room of 16C to 20C, with hats and extra layers off as soon as you come indoors. The wider advice stays the same whatever they're wearing: on their back, on a firm, flat mattress, in a clear cot, in the same room as you for at least the first 6 months.

What clothes cost

The Minimum Income Standard (MIS), from Loughborough University, is the one source we found with a per-child figure. Its 2026 calculator gives a clothing addition of £12.76 a week for a child aged 0-1, and £10.02 for the next band up, from age 2.

That's about £665 a year at the younger rate, by our sum. MIS is what the public agrees is a minimum, and it isn't average spending. Its authors say it isn't a personal budgeting tool. The figure also describes a toddler's clothes and shoes, so it says little about a newborn's first months. We found no source that prices clothes by size, and we won't split that total up across them.

Most main items on the MIS list have a life of about 26 weeks. So expect to replace clothes roughly every 6 months, at least on that list.

Second-hand is a full choice

Babies outgrow clothes quickly, which is why second-hand makes sense to me. Hand-me-downs and charity shops are a real alternative to new, and our catalog marks these packs fine to buy second-hand after a look for damage.

We have no measured figure for how much that saves. Our calculator uses 50% off new, and that's our own estimate. Change it to suit what you actually pay in the three-year cost calculator.

Our guide to what's fine to buy second-hand goes item by item, and the first-year cost guide shows where clothes sit next to everything else.