Generally, a calendar year has 2,080 work hours if the calculation is based on a standard 40-hour workweek. If you work less than 40 regular hours every week, there are several ways to figure out how many hours you've worked in any given year. When figuring your work hours for the year, it is important to keep the pay frequency and the number of hours worked for each pay period in mind.

Calculate work hours for the year based on a weekly pay cycle. For instance, say you worked 40 hours each week. There are 52 weeks in a year. Calculate as follows: 52 weeks x 40 hours = 2,080 hours for the year.

Figure work hours based on a biweekly pay period. Suppose you worked 35 hours each week; a biweekly pay cycle has 26 pay periods and payment is made every other week. Calculate as follows: 35 hours x 2 weeks = 70 hours; 70 hours x 26 pay periods = 1,820 hours for the year.

Determine work hours based on a semi-monthly payroll. A semi-monthly pay period occurs twice a month, and has 24 pay periods containing 86.67 regular hours each. Generally, semi-monthly employees are paid on a salaried basis and are therefore paid a set wage each pay date. Calculate as follows: 24 pay periods x 86.67 = 2,080 hours for the year.

Deduct federal holidays, if applicable. As of 2010, there are 10 federal holidays; therefore, deduct 80 hours (10 days x 8 hours = 80 hours) from each calendar year's hours to arrive at the total hours worked. For example, if you are a salaried employee on a biweekly payroll, calculate as follows: 26 pay periods x 80 hours = 2,080; subtract the 80 holiday hours from this amount to come up with 2,000 hours worked.