Moving up a size: when to buy and what to count

Signs it’s time

Babies rarely outgrow everything on the same day. Usually a few pieces start to feel wrong, and then suddenly most of them do. Watch for:

• Snaps that strain or gape at the nappy, or are hard to close.
• Toes pressing against the end of footed sleepsuits, or fabric pulling tight when your baby stretches their legs.
• Sleeves and legs riding up, leaving wrists and ankles showing.
• Necklines that are a struggle to get over the head.
• A length measurement near the top of their size on our size guide. The size chart by age, height and weight explains how to measure.

Have a few pieces ready before you need them

Growth spurts can make a size change feel like it happened overnight. To avoid a morning with nothing that fits, keep three or four pieces in the next size ready on a shelf before the switch: a couple of sleepsuits and one day outfit is enough. That small cushion gives you time to do the audit below and buy only what you need, rather than rushing out for anything that fits.

Moves that catch parents out

• 0–3 to 3–6 months: often sooner than expected, especially for babies born on the larger side, some of whom barely use the first size.
• 3–6 to 6–12 months: usually arrives with sitting up and first foods, so the new size needs more tops than the last one.
• 6–12 to 12–18 months: can come well before the first birthday, and walking changes what gets dirty, from tops to knees.
• 12–18 to 18–24 months: toddlers often grow taller before they fill out, so trousers turn short while tops still fit.

The audit, in five steps

• Gather everything you already have in the next size: gifts, hand-me-downs, things bought ahead, pieces from the grandparents’ house.
• Try on one or two to check the size really is right for your baby, as makers vary.
• Count by type: sleepsuits, bodysuits, day sets or separates, layers, outer layer.
• Compare the count with the number you need for your washing routine.
• Check the season. Ten summer rompers don’t help if the next size will be worn in December.

Buying the gaps

Whatever is short after the audit is your shopping list. Start with the pieces you use every day, usually sleepsuits and bodysuits for young babies and day sets for older ones. Our rompers and sleepsuits cover the first; sets cover the second. Add one warm layer if the new size falls in winter. Leave occasion outfits until you know the date and size.

When a new piece arrives, try it on straight away. We exchange unused pieces in their original condition with the original bill within 7 days, so checking the fit early matters; the details are on our delivery and returns page.

Don’t clear out the old size too fast

Some pieces last longer than others. Stretchy ribbed knits, joggers with a turned-up hem that can be let down, and dungarees with adjustable straps often fit for weeks after the sleepsuits have gone. Tops and bottoms can outgrow at different speeds too. Keep whatever still fits comfortably in the current-size drawer and move the rest to the outgrown basket.

Our wardrobe switch checklist shows how to set up drawers so the switch is quick.

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