The month (mo) is a time unit averaging approximately 30.44 days or 2,629,746 seconds, used for billing cycles, lease agreements, and financial planning. Calendar months vary from 28 to 31 days, but the average month provides a consistent reference for long-term calculations. One average month equals roughly 4.345 weeks or about 730.5 hours.

The year (yr) is a time unit equal to approximately 365.25 days or 31,557,600 seconds, representing one full orbit of the Earth around the Sun. It is the primary unit for age, financial reporting, interest rates, and long-term contracts, with the quarter-day surplus handled by leap years. One year equals roughly 52.18 weeks or about 8,766 hours.