Children's clothing size 3–6 months: how long it lasts and what to do afterwards

Between weeks 12 and 26, the pace of growth is still very fast. It's common for a garment that fits perfectly at week 12 to no longer close properly by week 18. Add to that the variation between brands: a size 3–6 from one brand can be equivalent to the 6-month size from another.

The result is that many families unknowingly buy too much for this stage, or the opposite: they receive clothes as gifts in this size and the baby has already grown past it by the time it comes to use them.

The key is having few but versatile items. For day-to-day use, five or six bodies, two or three pairs of trousers, and some warm layers depending on the season are usually enough. Turnover is high and washing is frequent, so there's no need for much more.

Prioritise garments that are easy to put on and take off. Fastenings at the crotch and neck make a real difference when you're changing three times a day. Nice design is fine, but practicality matters more at this stage.

A clear signal is when bodies start to feel tight at the shoulders or the feet of a sleepsuit no longer close properly. Don't wait until garments are uncomfortable before you start organising the next lot.

Having size 6–9 or 6–12 months to hand before you need it avoids emergency purchases. If you can get it in advance, whether inherited, bought second-hand, or through a swap, the transition becomes much less stressful.

If the clothes are in good condition, it makes a lot of sense for them to circulate quickly. The 3–6 month size is one of the most in-demand because there are always newborns. Donating, swapping, or passing them to a family you know is usually the most straightforward option.

If you decide to keep them for a possible second child, do it properly: clean lot, clear size, season noted. A box with no label and a mix of sizes is far less useful than a well-organised one when the time comes.