To measure your childs size, grab the tshirt that fits them the best in your opinion. Take the chest measurement(armpit to armpit x2) and the armpit to hemline and compare it to the sizing. I would not go less than .5inch/1cm. You can size up pretty generously with knitwear. The lay is more gentle than an average cotton shirt.
Arm Pit to Hemline- 4.5 inches/11.5cm
Chest- 18 inches/47cm
All Briggs and Craft knits designs are crafted for adventure, creating heirloom pieces that are original & tested to the max by my sweet kiddos.