Baby Clothing Size Guide
Babies grow fast, and sizing labels vary by country and brand. Use our detailed chart to match your baby's age, height, and weight to the correct clothing size across US, UK, and EU standards.
Quick Converter
| Age | US Size | UK Size | EU Size | Height (cm) | Weight (lbs) |
|---|---|---|---|---|---|
| Preemie | Preemie | Tiny Baby | 44 | 43-46 | Up to 5 |
| Newborn | NB | Newborn | 50 | 46-51 | 5-8 |
| 0-3 months | 0-3M | 0-3M | 56-62 | 51-62 | 8-12 |
| 3-6 months | 3-6M | 3-6M | 62-68 | 62-68 | 12-16 |
| 6-9 months | 6-9M | 6-9M | 68-74 | 68-74 | 16-20 |
| 9-12 months | 9-12M | 9-12M | 74-80 | 74-80 | 20-24 |
| 12-18 months | 12-18M | 12-18M | 80-86 | 80-86 | 24-28 |
| 18-24 months | 18-24M | 18-24M | 86-92 | 86-92 | 28-30 |
| 2 years | 2T | 2-3Y | 92-98 | 92-98 | 30-33 |
Click any row to highlight it. Sizes are approximate and may vary by brand.
How to Measure Your Baby
Measure Height
Lay your baby on a flat surface. Gently extend their legs and measure from the top of the head to the soles of the feet. Height is the most reliable indicator for baby clothing size, more so than age.
Check Weight
Weigh your baby at a recent pediatrician visit or at home using an infant scale. Weight helps narrow down the size when your baby is between height ranges or has a stockier build.
Size Up When in Doubt
Always choose the larger size if your baby is between sizes. Babies grow quickly, and slightly roomier clothing is more comfortable and lasts longer. EU sizing is based directly on height in centimeters, making it the most precise system.
Sizing Tips by Garment Type
Different baby garments have unique sizing considerations beyond the standard age-based chart.
Onesies & Bodysuits
These need to snap comfortably at the crotch without riding up. If your baby is long-torsoed, size up even if the weight is in the lower range to prevent uncomfortable pulling.
Sleepers & Footies
Foot length matters here. Footed sleepers that are too short in the foot can curl toes and restrict movement. Size up once your baby's toes press against the end.
Outerwear & Jackets
Always buy outerwear one size larger to layer over other clothing. A coat that fits perfectly over a diaper shirt will be too tight over a sweater in winter.
Hats & Accessories
Baby head circumference grows rapidly. Measure around the widest part of the head above the ears. Stretchy knit hats are more forgiving than structured styles.
Frequently Asked Questions
Should I buy by age or by measurements?
Always prioritize measurements over age. Babies at the same age can vary dramatically in size. A tall 6-month-old may need 9-12 month clothing, while a petite baby of the same age may still fit 3-6 month sizes. Height is the single best predictor of clothing fit for babies.
What does EU baby sizing mean (50, 56, 62)?
European baby sizes correspond directly to the baby's height in centimeters. Size 56 is designed for a baby approximately 56 cm tall. This makes EU sizing the most straightforward system since you only need to know your baby's length.
How long will each size last?
On average, babies move through a size every 2-3 months in the first year, slowing to every 3-4 months in the second year. Growth spurts can be unpredictable, so avoid buying too many items in a single size too far in advance.
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