This tank top has a "retail fit", which means it's more of a style-driven cut than a standard, boxy adult cut tank top. It does run smaller, as a result. Our best advice for choosing a size:
If you like your shirts tight, go with the size you normally wear. If you like your shirts form fitting, but not too tight, go one size up from a standard/average size tank top you would buy. If you like your shirts loose, go up two sizes.
Ladies, the armholes are larger than a traditional women's tank top, so you'll probably want to layer underneath.
S - Small - fits 34"-37" chest M - Medium - fits 38"-41" chest L - Large - fits 42"-45" chest XL - Extra Large - fits 46"-49" chest 2XL - Double Extra Large - fits 50"-53" chest