Age labels on children's clothing are broad guides. Two children of the same age can need different lengths or proportions, and retailer sizing can vary, so it helps to check height and measurements alongside the age band on the label.
UK Baby and Children's Clothing Size Chart
Most major UK retailers use similar age-to-height ranges, though exact cuts vary by brand. Use this as a general starting point, then check the specific retailer's own size chart before ordering.
| Age band | Approx. height | Approx. weight |
|---|---|---|
| Newborn | up to 50cm | up to 3.5kg |
| 0-3 months | 50-56cm | 3.5-6kg |
| 3-6 months | 56-63cm | 6-8kg |
| 6-9 months | 67-72cm | 8-9.5kg |
| 9-12 months | 72-80cm | 9.5-11kg |
| 12-18 months | 80-86cm | 11-12.5kg |
| 18-24 months | 86-92cm | 12.5-14kg |
| 2-3 years | 92-98cm | 14-15.5kg |
| 3-4 years | 98-104cm | 15.5-17.5kg |
| 4-5 years | 104-110cm | 17.5-19.5kg |
| 5-6 years | 110-116cm | 19.5-21.5kg |
| 6-7 years | 116-122cm | 21.5-24kg |
| 7-8 years | 122-128cm | 24-27kg |
Use Height and Measurements
When a chart includes height, chest or waist, compare those numbers with the child rather than choosing only by age. For babies, allow comfortable movement without excessive loose fabric.
Consider Season and Growth
Buying far ahead can mean the item fits in the wrong season. For coats and sleepwear, also consider the layers worn underneath and follow relevant safety guidance.
Check Practical Details
Easy fastenings, adjustable waists, reinforced knees and washable fabrics can matter more than decorative details. Review multipack quantities so an apparent saving does not create waste.
Quick Checklist
- Measure height before ordering.
- Use the retailer's own chart, since sizing can differ between brands.
- Account for layers and season.
- Keep returns practical and timely.
Frequently Asked Questions
Are baby clothing sizes the same across all UK retailers?
No. Age labels are a general guide, and the same age band can fit differently between retailers. Always check the retailer's own height and weight chart where available.
Should I size up for a growing baby?
Sizing up slightly can extend how long an item is wearable, but very loose items are not advisable for younger babies for safety and comfort reasons. Balance growth room against a proper fit.
What if my child is between two sizes on the chart?
When a child falls between two size bands, choosing based on the higher of height or chest/waist measurement, rather than age alone, usually gives a better fit.
Before You Buy
When uncertain, compare measurements with a well-fitting item at home and avoid buying too many pieces in an untested size. Before you order, it's also worth checking our Baby & Child voucher codes and deals for current offers from UK retailers.
Editorial note: Prices, availability and retailer terms can change. Check the retailer website for the latest information before purchasing.