Women's jerseys have a slender tapered cut, not boxy like the men's jerseys. Order one size up if you like your jersey to fit looser.
Measure around the fullest part of your chest under the arms for your total chest circumference.
In general, NFL Jerseys will fit a little larger, but that depends on the jersey type. We recommend buying the next size up jersey if you plan on wearing clothes underneath (hoodies, t-shirts, etc).