Coat off, straps snug, blanket on top.
Bulky layers compress in a crash and leave the straps loose — even when they feel tight.
1. Take the puffy jacket or snowsuit off. 2. Buckle the straps snug against thin layers. 3. Tuck the jacket or a blanket over the top, arms out.
Short trips feel cold-proof either way — the rule matters for safety, not comfort.
What goes under the straps
Thin, close-fitting layers, the American Academy of Pediatrics says: leggings and long-sleeved bodysuits. A hat, mittens, socks or booties are fine.
Buckle up first, snug enough that you can't pinch the strap, then the blanket goes on top.
What goes over them
A blanket laid over the buckled harness, or the coat worn back to front over it. In the app, the Car seat option puts a blanket over the straps wherever the jacket would be.
Once the car warms up
Take the hat and outer layers off in a warm car, bus or train, the NHS says, just as you would indoors.