Most people answer this question with the wrong comparison. They look up the average US salary, or ask what a friend in another industry earns, and end up comparing themselves against the whole labor market instead of against the people doing their job. The average across all occupations tells you almost nothing about your own pay, because the spread inside a single occupation is usually wider than the gap between occupations.
The comparison that actually answers the question is a percentile inside your own occupation, in your own state. If you earn more than 68 percent of the people doing your job where you live, you are paid above the middle of that market and you know it precisely. If you are under the 25th percentile, three quarters of the people in your job and your state are paid more than you, and that is a fact you can take into a conversation with your manager.
The federal government publishes exactly this. The Bureau of Labor Statistics surveys employers rather than workers and reports, for every occupation, the wage at the 10th, 25th, 50th, 75th and 90th percentile nationally, plus the quartiles for each state. The tool above places your pay on that curve for the 917 occupations with published wages.