Go to your wireless provider's website or the phone manufacture's website and you'll find the phone's dimensions there. Given that, you can compare their dimensions to your current phone's dimensions and with a ruler could could even compare that to the depth of your jersey pockets. FWIW, I have a Galaxy S5 (14.2 cm long) and all my jerseys' pockets are deeper than the length of the phone by a good margin.

If carrying it my jersey pocket, I put the phone in a plastic bag to protect it from sweat, even though it's water resistant.