A disc's weight is generally found on the bottom of the disc. The manufacturer may emboss or engrave the weight or put a small sticker on the disc with the weight in grams. Some manufacturers just write the weight on the back or rim with a pen or sharpie.  Sometimes the weight will be to the gram and other times just a range of several grams, i.e. 173-5, will be indicated.

Weight Ranges

• Standard: 160g to 180g
• Lightweight or "Air": 145g to 165g
• 150 Class: 110g to 159g

Disc weight is regulated by PDGA rules. The rules set a maximum weight for discs that takes into account the diameter of the disc. Generally, drivers are limited to 175 grams and wider slow speed discs can go up to about 180 grams. With a perfect throw and a strong arm, heavier or max weight discs are the best choice. Heavier discs will be less affected by wind. The easiest way to consider what weight to throw is based on your grip strength. Discs are not "released" from your hand when thrown, they snap free from your hand with a tight grip. An average recreational player will often throw a 165-170 gram driver. More experienced players may throw the 175 grams discs. Very young players will need light weight discs. One of the signs of throwing a disc that is too heavy for the player is when the disc is releasing early. This is because the disc is not being gripped tight enough and the heavier weighted disc rips from your fingers too early. An early release will have less power/speed and is often released on a hyzer or "pre-faded" angle. This can be hard to diagnose when players have other form and disc selection errors as these can also be a hyzer release. If you are getting frustrated with your throw, try a lighter disc. It may be the solution. The down side to lighter discs is that they are pushed around by the wind more. This can helpfully provide extra distance when you have a tail wind, but is painful with any other kind of wind. One way manufacturers adjust the weight of discs is with very small air bubbles inserted during the molding process. These less dense discs are more likely to float in water. (though you will want to test this before potentially losing your disc). When starting out very young players, use the lightest discs you can.