This pattern comes in three sizes. The small size fits approximately 18-24 months.
The medium is approximately a 2T/3T. It is about 1 inch wider through the side panels and about ½” taller than the 18 month size.
The large size is approximately 3T/4T. It is 1” wider through the side panels and 1” wider through the tummy panel (a total of 2” wider), 1” taller, and the soaker pad is wider and taller than the 18 month size. The width between the legs is the same on all sizes as well as the height of the waistbands and leg bands.
The sizes correspond to my children’s trainers and underwear that I have purchased from the store.