Sizing — not just by age.

Babies are not standardised. Two healthy 6-month-olds can be 3kg and 5cm apart. Age-only sizing forces parents into the wrong fit half the time.

Our size grid runs by weight + height + chest measurement, with overlap between sizes so you can size up if your baby is mid-range.

Newborn (3.0–4.5 kg, 50–55 cm) — the first three to six weeks for most babies. 0–3m (4.5–6.5 kg, 56–62 cm). 3–6m (6.5–8.0 kg, 63–69 cm). 6–12m (8.0–10.0 kg, 70–76 cm). 12–18m (10.0–12.0 kg, 77–82 cm).

Each garment ships with a fold-out size card showing fit on real babies — not standardised forms.

Generous neckline so it slides over the head without forcing. Snug-but-not-tight body so it doesn't bunch. Leg-snap spacing matches a UK standard nappy.

A bodysuit should leave room for two adult fingers around the waist when fastened.

Sized differently — Newborn (3.0–4.5 kg), Small (4.5–6.0 kg), Medium (6.0–8.5 kg). Not by age. Bigger babies move up faster.

When the baby starts pushing arms strongly out of the swaddle (typically 8–14 weeks), it's time to transition to a sleep bag.

Combined sizing: 0–6m (3.5–8 kg, up to 71cm), 6–18m (8–13 kg, up to 86cm), 18–36m (13–18 kg). The longer-fit means one bag covers a whole stage.

Always size up. Premium fabrics shrink ~2% with the first wash; we'd rather a piece be just-large than just-small. The bag won't look loose around the chest because the design accounts for the size-up convention.