These are a size 5 with 6 length for my tall but lean 4-year-old. I only have the larger size range, otherwise I would have added length to a size 4, but these fit fine.
I decided to make some fun appliqués for the tees. The star and the lightning bolt on the Flash tee were just drawn free-hand on the paper side of some Heat n' Bond.
The Flash tee is made of a scrap of cotton interlock and the neckband and appliqué fabric are cotton/Lycra jersey. All the other tees are also made of cotton/Lycra jersey.
The triceratops and Batman appliqués were traced from online images, using my computer screen as a lightbox. I appliquéd the gray bat (fused to Heat n' Bond) to a scrap of yellow jersey, and then applied Heat n' Bond to the back of the jersey before cutting out the oval free-hand. It turned out so much better than I expected!
The gray shirt is actually cut from a tee I made my husband last year, (which he ripped a big hole into). The jersey, a lovely 10 oz cotton/Lycra from The Fabric Fairy, was too nice and too spendy to just throw away. I'm glad I was able to reuse it. Bonus, I cut G's little sleeves from the original sleeves, preserving the original hem, so that saved time too. I didn't actually hem the bottom of this one because I wanted to make sure he could wear it next year too (assuming he doesn't rip a hole in it also). And because I wanted to be done with the shirt.
Here are some rotten iPhone photos of G in his tees. You can see how long the sleeves are, and that is after I shortened them by at least an inch (I don't actually remember). The sleeves on this pattern run quite long.
G is thrilled with his new tees. I'm thinking of making a Robin tee for Niko so they can be Batman and Robin. But really I just want to get back to sewing for myself.