Date Difference Calculator
Count the days, weeks, business days and years, months and days between two dates, or add and subtract days, weeks, months, years or business days.
Free · No sign-up · Your inputs stay in your browser
Input
Days between dates, or a date plus a period
Output
66 days
Calendar difference
0 years, 2 months, 5 days
| Days | 66 |
|---|---|
| Weeks | 9 weeks and 3 days |
| Business days | 48 |
| Hours | 1,584 |
| Seconds | 5,702,400 |
| End date is a | Friday |
Calendar dates in UTC, so a daylight-saving change never makes a day 23 hours long. Adding a month to the 31st lands on the last day of a shorter month (31 January + 1 month = 28 or 29 February), the same rule as Carbon's addMonthsNoOverflow() and date-fns addMonths. Business days skip weekends but not public holidays.
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About this tool
Method, assumptions, practical next steps, and limits.
Month arithmetic is a choice
January 31 plus one month has no right answer. This tool, date-fns' addMonths and Carbon's addMonthsNoOverflow() clamp to the last day of February; PHP's DateTime::modify('+1 month') and Carbon's plain addMonth() overflow into March 3 (or 2 in a leap year). Billing code should pick one behaviour on purpose.
Why UTC dates
Subtracting two local timestamps across a daylight saving change gives 23 or 25 hours for one 'day', and integer division then loses or gains a day. Calendar dates in UTC avoid it. Business days here skip Saturdays and Sundays only; public holidays differ by country and need a calendar.