Babies grow SO fast! That's why we designed our sleepwear to be extra flexible in sizing. Our zippies have extra length (easily roll up any extra), foldable foot cuffs (traditional footies are so limiting) and super stretch for longer wear! They are designed to fit snug in accordance with all CPSC guidelines (as they are not treated with any nasty chemicals!). Read more about the breathability and benefits of our fabric here.
The below guides are based on feedback from hundreds of customers.
We recommend sticking to true size/age for the Zippy - they run true to size to generous and are designed to fit 2-3x longer than your average sleeper.
If you need other specific measurements or a sizing recommendation, don't hesitate to contact us.