Date Calculator – Days Between Dates, Age, Business Days & More
This Date Calculator brings together several common date and time tools in one place. You can quickly see how many days are between two dates, add or subtract days from a date, calculate age, count business days, and find the ISO week number of any date.
1. Date Difference Calculator
The Date Difference mode shows how many days, weeks and approximate years, months and days are between two dates. You can choose:
- Exclusive: Do not count the start date.
- Inclusive: Count both the start and end date.
If inclusive: Total days = (End date − Start date) + 1
2. Add or Subtract Days, Weeks, Months, Years
The Add/Subtract mode lets you move forward or backward in time from any starting date. Choose the unit (days, weeks, months, years) and the calculator shows the new date.
3. Age Calculator
Enter a date of birth and an optional "as of" date to see:
- Age in years
- Years, months and days
- Approximate total days lived
- Next birthday date
4. Business Days Between Two Dates
The Business Days mode counts Mondays to Fridays between two dates and separates weekdays from weekend days. Holidays are not included, so it is a simple working days calculator.
5. Week Number (ISO Week Date)
The Week Number mode uses the ISO week date system, where weeks start on Monday and week 1 is the week with the year's first Thursday.
Use Cases for the Date Calculator
- Planning trips, deadlines, and schedules.
- HR and payroll date differences and workdays.
- Student assignments and school schedules.
- Personal tracking such as age, anniversaries and milestones.
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