I got it xl and the Superman shield looks hilariously out of proportion. I'd surmise the small/medium would be ok. Plus the tee quality isn't the same as the regular Old Navy old school Superman tee. I thought that was weird.

Got size medium, shirt ran small. Quality was not very good. The brand of the shirt was Gildan, like the inexpensive shirts they sell at the craft stores. The brand was not disclosed in the picture or product description. The logo was not good quality, and looked like it would crack. The superman logo also had some lines going through that look like a defect.

Logo is proportionally smaller than the image shown, print is blurry and printed on a Gildan 3 dll shirt.