Although each state uses its own formula to calculate benefits, all states use the applicant's prior earnings in their calculations. Because unemployment compensation is intended to partially replace your income, the amount you will receive depends on how much you used to earn. Most states use an applicant's earnings during the highest paid calendar quarter of the base period as a starting point (in most states, the base period is the earliest four of the last five complete calendar quarters the employee worked before becoming unemployed). Some states use the two highest paid quarters of the base period; others look at the applicant's prior annual earnings.
Once this amount is calculated, the state then uses a multiplier, based on what percentage of wages it replaces, to come up with a weekly benefit amount. For example, a state that uses the applicant's highest paid quarter (13 weeks) and replaces half of the applicant's wages would multiple the total earnings in the highest paid quarter by 1/26 to come up with a weekly benefit amount.
This isn't the last step in the process, however: Every state also has minimum and maximum benefit amounts. No matter how much you used to earn, you can't collect more than the maximum weekly amount. Some states also pay a bit more per week to applicants with dependents.