Date Difference Calculator

About the Date Difference Calculator

The date difference calculator tells you how much time lies between two dates: the total number of days, the same period in years, months and days, in weeks and days, in hours and minutes, and how many of the days are weekdays (Monday to Friday) or weekend days.

A second mode adds or subtracts days, weeks, months or years from a date, for example to find a due date 90 days from today, the end of a 6-month notice period or the date 2 weeks before an event. Results are for general information; check important deadlines against the rules that apply to you.

All calculations use whole calendar days in the proleptic Gregorian calendar (today's calendar, extended backwards) and run in your browser. Time zones and daylight-saving changes cannot shift the result, because no clock times are involved.

How to use it

1. Choose "Between two dates" or "Add or subtract".
2. For a difference, pick the Start date and the End date. Both default to today; the Today buttons reset a field.
3. Tick "Include end date" if the last day should count as a full day, for example for the length of a holiday or a rental period.
4. Read the results: total days, years/months/days, weeks, weekdays, weekend days, hours and minutes. If the end date is before the start date the result is shown as negative; use Swap dates to reverse it.
5. To add or subtract, pick the start date, choose Add or Subtract, enter a whole number and select days, weeks, months or years. The resulting date and its weekday appear immediately.
6. Use "Use as start date" to chain several steps, or Reset to start over.

Features

• Many ways to express a duration: Total days, a years–months–days breakdown, weeks plus days, and calendar-based hours and minutes (24 hours per day).
• Weekday count: Counts Monday–Friday and Saturday–Sunday days in the period, which helps with rough working-day estimates.
• Correct month arithmetic: Adding months keeps the day of the month where possible and otherwise uses the last day of the month: 31 January + 1 month is 29 February in a leap year and 28 February otherwise.
• Leap years handled: Uses the Gregorian leap-year rules (every 4 years, except century years not divisible by 400), so 2000 was a leap year and 2100 will not be.
• Private and offline-friendly: Everything is calculated on your device; the dates you enter are not sent anywhere.

Examples

Limitations and notes

• Public holidays, company closures and regional working weeks are not considered; the weekday count only excludes Saturdays and Sundays.
• Only whole days are calculated. Hours and minutes are calendar-based (24 hours per day) and do not account for daylight-saving changes or time zones.
• Dates before the introduction of the Gregorian calendar (1582, later in many countries) are calculated as if the calendar had always been in use (proleptic Gregorian), so they may not match historical records.
• Supported years are 1 to 9999.
• A years–months–days breakdown is not unique when months have different lengths. This tool counts whole months forward from the earlier date and clamps to the end of shorter months; other calculators may use a different convention.

Frequently asked questions