How Many Weeks Are in a Year (and a Month)?
How many weeks are in a year? 52 weeks plus 1 day (2 in a leap year). Learn why, when a year has 53 weeks, and how many weeks are in a month.
Dates & Time
Dates & Time
Find examples for date intervals, working days, deadlines, elapsed time, and time zones. Use the date difference calculator, time zone converter, or age calculator. Calendar-day counts, overnight stays, and working-day counts can use different inclusion rules.
Dates & Time
How to Calculate Business Days Between Dates
How to calculate business days between dates: subtract weekends and public holidays from the total. Includes a worked example and a quick estimate.
Dates & Time
How to Calculate Age From Date of Birth
Year subtraction gets age wrong half the time. The correct method, months-and-days, leap-year birthdays, and other age systems.
Dates & Time
How to Calculate Days Between Two Dates
Subtract the dates, mind the leap day, and decide inclusive vs exclusive counting – the source of most off-by-one errors.
Dates & Time
Countdown Timers: How to Count Down to Any Event
How a countdown works, where it helps, the deadline psychology, and the time-zone catch on shared countdowns.
Dates & Time
How to Convert Time Zones (UTC, GMT, and Offsets)
Convert through UTC every time, mind half-hour zones, and watch the daylight-saving trap that changes the gap between cities.