By Ziv Shay | Updated April 2026
Calculate days between dates, count business days, find your age, and more
Counts only weekdays (Monday-Friday), excluding weekends.
Our calculator computes the exact difference in milliseconds between two dates and converts it to days, accounting for leap years, daylight saving time, and varying month lengths. The result is always accurate to the second.
Business days (also called working days or weekdays) are Monday through Friday. Our business days calculator excludes Saturdays and Sundays from the count. Note that public holidays are not excluded as they vary by country and region.
Age is calculated by finding the difference between your birth date and today's date. The calculator accounts for leap years and gives you your exact age in years, months, and days. It also shows your age in total days, hours, and minutes lived.
A leap year occurs every 4 years, with century years being exceptions unless divisible by 400. Leap years have 366 days instead of 365, with February having 29 days. The years 2024 and 2028 are leap years. Our calculator handles all leap year calculations automatically.
To calculate weeks, our tool first finds the total number of days between two dates, then divides by 7. The remainder tells you the extra days beyond complete weeks.
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Date calculations are surprisingly common in everyday life and business: How many days until a deadline? What is the date 90 days from now? How many business days between two dates? How old am I in exact days? Whether you are planning a project timeline, calculating contract terms, determining pregnancy due dates, or figuring out how many days until your next vacation, this tool provides instant, accurate results.
Calendar math is deceptively tricky because months have different lengths (28-31 days), leap years add an extra day every four years (with exceptions for century years), and business day calculations must account for weekends and holidays. Our calculator handles all of these complexities automatically, supporting both simple date differences and advanced calculations like adding weeks, months, or years to any starting date.
Days between dates: Used for project planning, countdown to events, interest calculations (many financial formulas use actual days), age calculations, and determining time elapsed. A year contains 365 days (366 in leap years), which is 52 weeks and 1 day, meaning the day of the week shifts by one each year (two after a leap year).
Business days: Critical for legal deadlines, delivery estimates, project management, and payment terms. "Net 30" payment terms typically mean 30 calendar days, while "30 business days" is approximately 42 calendar days. The average month contains roughly 21-22 business days. Courts, government agencies, and financial institutions often calculate deadlines in business days.
Add/subtract time: Adding or subtracting days, weeks, months, or years from a date is essential for calculating warranty expiration dates, subscription renewals, rental agreement end dates, medication refill schedules, and any time-based planning. Adding months can be ambiguous (what is one month after January 31?) since months have different lengths, so conventions vary.
A common year has 365 days. A leap year has 366 days. Leap years occur every 4 years, except for years divisible by 100 (not leap years), unless also divisible by 400 (leap years). So 2024 was a leap year, 2100 will not be, and 2000 was. The average calendar year is 365.2425 days long, which is why we need the leap year system to keep our calendar aligned with Earth's orbit.
Count all days between the two dates, then subtract weekends (Saturdays and Sundays). For a rough estimate, multiply the number of weeks by 5 and adjust for partial weeks. For precise calculations that include holidays, you need to also subtract any federal or company holidays that fall within the range. Our calculator handles this automatically.
The "90-day rule" appears in many contexts: probationary employment periods (employers often set a 90-day review period for new hires), visa-free travel limits (the Schengen Area allows 90 days within any 180-day period), return policies (many retailers offer 90-day return windows), and health insurance qualifying events (you often have 90 days to enroll after a life change). Our calculator makes it easy to determine the exact date 90 days from any start date.
Enter your birthdate and today's date into the calculator to get your exact age in years, months, and days. You can also see your age in total days, weeks, hours, and minutes. This is useful for passport applications, legal documents, and medical records that require precise age calculations. Fun fact: if you are 30 years old, you have been alive for approximately 10,957 days.
There are 52 weeks and 1 day in a common year (52 weeks and 2 days in a leap year). This means there are not exactly 52 weeks in a year, which is why dates shift by one day of the week each year. A quarter (3 months) contains approximately 13 weeks. These calculations matter for payroll (biweekly pay results in 26 paychecks per year, not 24), budgeting, and project scheduling.
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