7 baby clothes sizing traps: what actually fits

The bodysuit came out of the wash and would not close over the baby’s shoulders. It was 6:40am on a Thursday in August 2024, week five with our first. The tag said 0-2 months. She was five weeks old and squarely inside the promised window; she was done with it anyway.

Baby clothes sizes are height bands with a month number bolted on. The month number lies; the height does not. A size 62 fits a baby up to 62 centimetres; the fabric does not care how old she is.

We bought baby clothes twice: once in the 2024 fog with our first, once on purpose with our second. These are the seven sizing traps from those two years, with the fix that came out of each.

The whole list at a glance, then each trap in detail.

1. The month number is a rumor

On the back of that tag were two numbers. One said 0-2 months. The other said 56, the height in centimetres the garment was cut for. The first number lied; the second was already true. She had measured past it at the U3 earlier that week; the booklet had the proof.

The checkups run U1 to U9 across the first six years, per the official German U-checkup guide. The yellow booklet logs each visit’s measurements; it is the only sizing chart we trust.

Our rule: read the height, buy one size up. Sleepers and bodysuits get the bigger number; the cute outfit is bought exact and worn twice.

Where it fails: the rule assumes every brand means the same 68. It does not. That is trap two.

2. The brand lottery: 68 is not 68

A size 68 from two brands is two different shirts. In spring 2026 I sorted the boxes from the toddler’s first year for our second. The toddler “helped” by pulling everything onto the floor, while the baby watched from the bouncer.

Two sleepers, both marked 68, one from H&M and one from C&A. One was long and narrow; the other short and wide. They did not look like the same size, because they were not; that ended our trust in the label.

We keep one or two brands we trust for her current shape. Everything else gets the flat-lay test: lay the stranger over a known good sleeper, shoulder to hem. Body length first, sleeves and legs second.

The catch: babies change shape between sizes. A brand that fits a chunky baby at 62 can be wrong at 74, when the legs suddenly lead; we re-test at each size change.

3. The newborn stash: weeks, not months

Newborn sizes are the shortest-lived clothes you will ever buy. With our first, I bought the stash the marketing sold: ten sleepers in 50, eight bodysuits, three coming-home outfits. She was born in July. The 50s were done by the third week of August; I bagged them for a colleague. Most of the bag had never been worn. The fog that sold me the diaper bag we barely used sold me those sleepers too.

Second time around we bought almost nothing; the boxes from the toddler’s first year covered most of it. Every bag got its closing date on the tape; that became the log. The pattern lives in the chart. Sizes stretch as growth slows; newborn sizes stay the short ones.

The fix is boring: six sleepers in the current size, the rest mostly one size up. The first six weeks needed less than the marketing said; clothes were the loudest example.

Where it fails: the drawer still overflows, because babies leak and the machine runs daily. It beats the bag that never opened.

4. The season gamble: January bought in July

A sale price only counts if the size survives until the season. The navy snowsuit sat in the July sale of 2024, back when our first was still an only child. Size 62, half price; the tag said 3-6 months; she would be six months in January. I called it planning. The partner called it a guess about January, and she was right.

She grew into 68 in December, a month before snowsuit season started. The suit hung in the hallway all winter, then went into the donation bag with the tags on.

The rule: buy for the season you are in, one size up at most. Seasonless basics are the only thing we buy ahead; a pack of bodysuits does not care about the month.

Where it fails: the seasonal stuff really is cheaper in the sale, which is the whole trap. We buy it while she is in the size, not a season ahead. The full price is the price of a size that fits.

5. The gift pile: sizes the giver hopes for

Gifted clothes arrive in the size the giver hopes for, not the size the baby is. In October 2024 a package came from Oma and Opa in Flensburg. It held six sleepers in size 50 and one bodysuit in 74, marked “for later”. She had been out of 50 since August; the 74 was the size that eventually worked.

We answer in centimetres now: “She is 55cm. Anything from 62 up fits; 68 will fit soon.” The size-up default is the giver’s friend: too big waits, too small never gets worn. By baby two, the Flensburg package was all 62s and 68s; saying the size out loud had worked.

Where it fails: a size-up gift can still miss the season. A summer dress in 74 does nothing for a Berlin January.

6. The spurt tax: the size that quit in a week

Growth spurts do not respect the set you just bought. Late February 2025: the 68 sleepers closed fine on Monday. By Friday the feet would not stretch and the shoulders pulled; over that weekend she grew into 74. The six-pack of 68s I ordered ten days earlier arrived that Tuesday; three of the six were ever worn.

The rule that ended this: when a size gets snug, buy the next size in twos. Two sleepers, two bodysuits; if the spurt keeps going, buy two of the one after. You can always buy more of the size you are in. You cannot un-buy the set of the size you just left.

Where it fails: some spurts skip a whole size, so the twos get skipped with it. Tags stay on until the first wash, so the skip costs nothing but a donation bag.

7. The secondhand lie: labels that lie twice

Used clothes lie twice: the label is cut out, and the cotton has already shrunk. Most of our kids’ clothes are secondhand; that is the plan, not the fallback. The used-buying rules we keep cover the big gear; clothes needed their own system.

In autumn 2024 I picked up a Kleinanzeigen bundle of twelve sleepers. Two still had tags; three had the labels cut out. One shrank a full size in its first wash: it said 68 and fit like a 62 afterwards. That one taught me the system.

The system: wash everything once, then sort; shrink happens in the first wash, not the second.

• Wash the bundle once, then sort.
• Lay each piece flat and measure shoulder to hem.
• Label it with the measured size, not the printed one.
• Bag by measured size with the closing date.
• The pieces that lied twice become cleaning rags.

Where it fails: flat-lay measuring is slow the first time and fast by the third. The kita version of the same idea lives in our spare-clothes system; the tape is one season earlier.

How we picked these

• Every trap is one we fell into, dated between August 2024 and spring 2026.
• We kept the traps that cost money or laundry and cut the ones that only cost annoyance.
• The size log exists where we kept one: every bag got its closing date.
• The fixes are the things we actually do now, not the things we wish we had done.
• Sizes are personal; your baby’s curve is their own. The rest of what survived year one is in our first-year gear check.

Filed under newborn. Everything we’ve written is in the archive. Our accuracy and sourcing rules live on the editorial policy page.