Kids’ pyjama sizes by age

Pyjamas use the same age labels as day clothes, so the height chart is the best guide. The bigger question is whether to size up.

Checked against UK retailer charts on 18 October 2026.

Pyjama size by age and height

Most UK pyjamas follow the shop's normal clothing sizes. These are Boden's heights for each label:

Should you size up in pyjamas?

For loose-fit cotton pyjamas, one size up is common if your child is near the top of the height range. Sleeves and legs can be rolled for a few weeks. Two sizes up tends to mean tripping over trouser legs.

Snug-fit or "close-fitting" pyjamas are different. They're designed to sit close to the body. Buy the true size so they stay that way.

Cotton can shrink a little in the first hot wash or tumble dry. If the care label says wash at 30–40°C and dry flat or on low, follow it and the size will hold.

The fire-safety label

Under the Nightwear (Safety) Regulations 1985, children's pyjamas sold in the UK must carry a label. Fabric that doesn't meet the flammability standard after washing must say "KEEP AWAY FROM FIRE" in red. Fabric that does can say "LOW FLAMMABILITY TO BS 5722". The label must be inside the neck or next to the size label. Whichever it says, keep children well back from fires and heaters.

Babies and toddlers

Under-2s often sleep in sleepsuits or a sleeping bag rather than two-piece pyjamas. If you're using a sleeping bag, follow the maker's size by weight. Tommee Tippee's Grobag sizes are 6–18 months (from 8.2 kg, 68–86 cm) and 18–36 months (from 11.3 kg, 86–98 cm). Layers by room temperature: what should a toddler wear to bed.