Blame me if the weather breaks … I have just converted his shirts (some of them) to short sleeved.
A simple chop and hem job using a ‘proper’ short sleeve shirt to get the length right. Just cut off an inch and a half below the intended hem line. Keep the chopped off bits for crafty projects.
Turn shirt inside out, press a hem along the intended length and then turn under the raw edge about a quarter of an inch. Press again, pin and stitch around the sleeve.
Tip: remove the bed from your sewing machine so you can turn the fabric as you sew. Tip 2: start stitching at the under arm seam so if there are any gathers (if the sleeve tapers) they can be hidden underneath.