A warm sleep sack for infants that’s easy to zip up around squirmy little legs, this knits up quickly in bulky yarn. You’ll want to use machine-washable and -dryable yarn; I used a little over 1.5 skeins of Stylecraft Life Bulky.

This is designed to fit infants at the 50th percentile of chest circumference and height from ages 3 months to 1 year. It’s trivial to modify this pattern for larger or smaller babies; make sure to cast on over a multiple of 4 sts + 2, make the body as long or short as you please, and change the zipper size accordingly.

Row gauge is not important for this pattern.