Date Calculator
Numbers & DatesAdd or subtract days, weeks, months, and years from any date. Calculate the exact difference between two dates and count business days with holiday support.
Tuesday, March 24, 2026
Tuesday, March 24, 2026
Same day
0 days total
0 weeks and 0 days
~0 months
About Date Calculator
The date calculator provides three powerful modes in one tool: add or subtract an arbitrary duration (days, weeks, months, years) to find a resulting date; compute the precise difference between any two calendar dates broken down into years, months, weeks, and days; and count the number of working/business days between two dates while optionally excluding public holidays. All calculations respect month-end overflow rules and leap years, so adding one month to January 31 correctly yields February 28 or 29.
Features
- ✓Add or subtract days, weeks, months, and years from any starting date
- ✓Calculate difference between two dates in multiple units simultaneously
- ✓Business day counter with configurable work week (Mon–Fri or custom)
- ✓Optional public holiday exclusion for major countries
- ✓Handles leap years, month-end overflow, and daylight saving transitions
- ✓Result date shown with full weekday and ISO week number
- ✓Timeline visualisation of the date range
- ✓Copy result as plain text or ISO 8601 date string
Common Use Cases
- Calculate a project deadline that is 90 business days from kick-off
- Find service contract expiry by adding 12 months to a start date
- Count how many days remain until a release or event
- Determine how many years, months, and days old a person or system is
- Calculate invoice payment due dates (net 30, net 60, net 90)
- Verify SLA response windows by counting business hours and days
- Plan sprint timelines by adding two-week iterations from a start date
Frequently Asked Questions
QHow does adding months handle month-end dates?
When you add months to a date that falls on the last day of a month (e.g., January 31), the result is clamped to the last valid day of the target month (February 28/29, April 30, etc.).
QWhat countries' public holidays are supported?
The business day counter supports public holiday calendars for the US, UK, Canada, Australia, Germany, France, and several other countries. Holiday data is updated annually.
QDoes the calculator account for leap years?
Yes. Adding one year to February 29 in a leap year yields February 28 in a non-leap year. All calendar arithmetic correctly handles the Gregorian leap-year rules.
QCan I calculate the difference in working hours instead of days?
The current tool operates at day granularity. For hour-level calculations including business hours, use the Time Tools feature which includes a duration calculator.
QWhat date format should I enter?
You can type dates in common formats such as MM/DD/YYYY, DD/MM/YYYY, or YYYY-MM-DD, or use the built-in calendar picker to avoid format ambiguity.