When to Size Up on Your Children's Wear (and What to Do With the Clothes They've Outgrown)
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Children rarely announce that they've outgrown their clothes. The clothes announce it for them: trousers that suddenly stop at the ankle, a bodysuit that takes negotiation to snap closed, sleeves that creep up to the forearm mid-play.
Every parent knows the moment. What's less obvious is when exactly to make the switch, how far ahead to plan, and — the question we care most about at Blueberry — what to do with the beautiful pieces your child has just grown out of.
This guide covers all three, including how our sellback programme closes the loop: the outgrown size goes out, store credit comes in, and the next size comes home.
The Telltale Signs It's Time to Size Up
Growth doesn't happen on a schedule, so rather than watching the calendar, watch the clothes. It's time to move up a size when you notice:
Length runs out first. Trousers sitting above the ankle, sleeves stopping short of the wrist, and bodysuits or rompers that pull tight at the shoulders when your child sits are the classic early signals. Children typically grow out of the length of a garment before the width.
Fastenings become a struggle. If snapping a bodysuit or buttoning a waistband has become a two-person job, the piece is done at that size — continuing to squeeze into it is uncomfortable for your child and hard on the fastenings.
Marks on the skin. Sock lines are normal; red marks at the waistband, cuffs, or nappy area after wearing are a clear sign the garment is now genuinely too small.
Movement looks restricted. Toddlers should be able to squat, climb, and reach with total freedom. If a piece limits any of that, it's outgrown regardless of what the label says.
The label disagrees with reality. Age-based sizing is only ever an approximation, and it varies noticeably between brands. French labels like Petit Bateau and Jacadi tend to run on the slim, tailored side, while American cuts like Ralph Lauren are often more generous. A child can be comfortably one size in one brand and the next size up in another — which is why we always recommend judging by fit, not by the number on the tag. (We list dual EU and age sizing on our products for exactly this reason.)
Should You Buy the Next Size Before You Need It?
In a word: yes — and this is where second-hand shopping quietly outperforms retail.
On the high street, buying ahead is a gamble against the seasons. The next size up is only stocked in the current season's range, so if your child hits a growth spurt in February, good luck finding the winter coat in the new size.
Pre-loved shopping doesn't work that way. Because our catalogue is built from clothes children have already grown through, every size is available all year round — coats in spring, swimwear in autumn, and the next size up in the staples whenever your child decides it's time. Buying one size ahead in the pieces you know you'll need is one of the smartest habits a parent can build, and Blueberry is designed to make it possible in any month of the year.
A practical tip: when you find a brand whose cut suits your child, buying the next size in that same brand removes almost all the guesswork. Fit consistency is one of the underrated advantages of sticking with quality labels.
The Other Half of the Question: The Clothes They've Outgrown
Here's the part of sizing up that most guides skip. Every growth spurt leaves behind a small pile of clothing — and when that pile is made up of premium brands in beautiful condition, it's genuinely valuable.
This is exactly what our sellback program is for. The process is deliberately simple:
1. Check your pieces. We accept gently-used items from premium brands — think Jacadi, Petit Bateau, Bonpoint, Catimini, Ralph Lauren, and the other labels we love — with minimal to no signs of wear. Freshly washed, no stains, holes, or broken fastenings.
2. Submit your list. For your first submission, we ask for at least five items via the form on our sellback page. Have a larger wardrobe clear-out on your hands? Email us at sell@blueberryshop.co and we'll send you a bulk template.
3. Receive your offer. We respond with an offer for the items that fit our current inventory needs — and this is where the choice gets interesting.
Bank Transfer or Store Credit: How to Choose
Every offer comes with two options: a bank transfer, or a higher value in Blueberry store credit.
The bank transfer is the straightforward route, and it's always there if you simply want the money. But for most families, the store credit option is the one that makes the whole system sing — because you're almost certainly about to buy the next size anyway.
Think about what's actually happening when your child sizes up. You have a set of outgrown premium pieces on one side, and a shopping list for the same wardrobe one size larger on the other. Store credit connects the two directly: the outgrown Jacadi dress helps fund the next-size Jacadi dress. And because the credit value is higher than the transfer value, choosing credit means your outgrown clothes stretch further toward the new wardrobe.
The Blueberry Loop, in Practice
Put the pieces together and sizing up stops being an expense spike and becomes a cycle:
Your child outgrows a set of clothes → you sell the pieces in great condition back to us → you take the higher store-credit option → you put that credit toward the next size, available year-round → and a season or two later, the loop turns again.
Each turn of the loop, the same quality wardrobe carries forward. The brands stay premium, the condition standard stays high, and a meaningful part of each new size is funded by the last one. It's better for your budget, and it's the circular economy working the way it's supposed to: beautiful clothes staying in motion between families instead of sitting in storage or heading to landfill.
Families who've been through the cycle tell us it changes how they buy in the first place. When you know a well-kept Petit Bateau bodysuit or Jacadi coat holds real sellback value, choosing quality brands becomes the practical decision, not the indulgent one.
A Few Habits That Keep the Loop Turning Smoothly
Store outgrown pieces properly. Clean, dry, and folded away promptly — condition is everything to resale value, and items graded higher are worth more when you sell.
Keep sets together. Matching pieces and complete outfits are always appealing.
Don't wait too long. The best time to sell an outgrown size is soon after it's outgrown, while everything is still fresh from its last wash and in the condition you remember.
Sell as you size up. Making the sellback submission part of your sizing-up routine means the store credit lands right when the shopping list does.
Frequently Asked Questions
How do I know my items qualify for sellback? We accept premium-brand children's clothing with minimal to no signs of wear — freshly washed, with no stains, holes, rips, or broken zippers, and all buttons and fastenings intact. Full details are on our sellback page.
Is store credit really worth more than the bank transfer? Yes — the store credit option is always offered at a higher value than the bank transfer, so if you're planning to shop the next size with us, credit is the better-value choice.
Can I buy the next size out of season? Absolutely — this is one of the biggest advantages of pre-loved. Our catalogue isn't tied to a retail season, so coats, swimwear, and everything in between are available in every size, all year round.
How many items do I need to sell? First submissions start at five items through the form on our sellback page. For larger quantities, email sell@blueberryshop.co for a bulk template.
What if my child is between sizes? Judge by fit rather than the label, and when in doubt, size up — children grow into clothes far more gracefully than they squeeze into them. Slim-cut French brands may warrant sizing up sooner than more generous American cuts.
Ready to turn the outgrown pile into the next wardrobe? Start your sellback in 3 simple steps, then browse the next size up across our full collection — every piece quality-checked and available year-round.