Date Difference Calculator

Date Difference Calculator measures the time between two calendar dates. It gives the total number of days, the same span as weeks and days, the calendar difference in years, months and days, and the equivalent hours, minutes and seconds. You can choose whether the end date itself is counted.

Counting days across month ends and leap years by hand is error-prone, and many online counters quietly shift by an hour or a day around daylight-saving changes. Working purely with calendar dates gives the same answer anywhere in the world, which matters for deadlines, notice periods, project plans and contracts.

1. Choose the start date.
2. Choose the end date (use Swap dates if you entered them the wrong way round).
3. Tick “Include the end date” if both the first and last day should count.
4. Press Calculate difference.
5. Read the totals, then copy or download the summary.

• Total days, weeks and days, and calendar years, months and days
• Total hours, minutes and seconds based on 24-hour days
• Optional inclusion of the end date
• Exact leap-year and month-length handling
• Daylight-saving safe — time zones are never involved
• Clear errors for missing, invalid or reversed dates, plus a one-click swap

• Decide up front whether your rule counts the end date — leave periods often do, durations usually do not.
• For ages and birthdays, the Age Calculator shows your age and next birthday.
• Remember that months have different lengths, so “1 month” is not a fixed number of days.
• Use total days rather than months when an agreement specifies a number of days.