Level is a ranking of your fitness level in relation to the other riders on Stages Flight. Level is calculated by ranking riders within each gender based on their FTP result and body weight. A rider who weighs more puts out more watts, while a rider who weighs less often puts out less watts to do the same effort, which is compensated for by factoring in weight to the score. As you train more, your fitness level increases and your level should improve. Note that your level can also decrease even when your FTP has increased or stayed the same if the FTP at the top of the leader board has also gone up.
Most riders will fall somewhere in the middle of the level spectrum. A new level is calculated each time you complete an FTP test. Following is the formula for the level calculation: