Date & Time Tools
Date Difference Calculator
Calculate the difference between two dates in years, months, weeks, days and business days (Mon–Fri). For a project, leave or any date span — not age from a date of birth.
Dates to compare
Include end date counts the final day. Business days are Monday–Friday and do not exclude public holidays.
Date duration
Calendar span
6 years, 7 months, 4 weeks
Years
6
Months
7
Weeks
4
Days
0
Total months
79
Total weeks
347
Total days
2,432
Business days (Mon–Fri)
1,738
Years, months, weeks and days are the calendar breakdown. Totals cover the whole span.
This is the span between any two dates. For age from a date of birth, use the Age Calculator. To add or subtract days, weeks, months or years, use the Date Calculator. To turn a duration into hours, use the Time Converter.
About this tool
This date difference calculator finds the duration between two calendar dates: years, months, weeks and days, then total months, total weeks and total days. It can also count business days from Monday to Friday. Use it for a project, leave, contract or trip. For how old someone is from a date of birth, use the Age Calculator instead.
How to use
- Enter the start date and the end date.
- Use Swap dates if the fields are in the wrong order.
- Turn on Include end date when the final day should count.
- Read the calendar span, the totals, and business days (Mon–Fri).
How date duration is calculated
Complete months follow the civil calendar. If the end day-of-month is earlier than the start day-of-month, a month is borrowed and that previous month’s length is added. When that month is shorter than the gap, such as 31 January to 1 March, another month is borrowed so the day count does not go negative. Total days are the exact number of midnights between the dates. Total weeks are total days ÷ 7, with the remainder kept as days. Include end date adds that final day. Business days count Monday–Friday only and do not remove public holidays. This is a date interval, not an age from a date of birth.
Worked example
15 January 2020 to 15 January 2026 is 6 years — 72 total months and 2,192 total days. 15 January 2025 to 15 March 2025 is 2 months. 15 January 2025 to 10 March 2025 is 1 month, 3 weeks and 2 days (1 total month, 7 total weeks, 54 total days), because 15 March has not been reached.
Months Between Two Dates
Months between two dates are complete calendar months, not total days divided by 30. A month counts when the same day of the month comes around again. 15 January 2025 to 15 March 2025 is 2 months. 15 January 2025 to 10 March 2025 is 1 month, 3 weeks and 2 days — 1 total month, 7 total weeks and 54 total days — because 15 March has not arrived. Total months adds 12 for each complete year. Days between two dates is the number of midnights from the start date up to the end date. Weeks between two dates is that day count divided by 7. Include end date counts the final day as well: 1 January through 10 January is 10 days instead of 9. Business days (Mon–Fri) uses the same range and skips Saturdays and Sundays. Public holidays stay in the count.
Frequently asked questions
Is this an age calculator?+
No. This page measures a generic duration between any two dates: days, weeks, months and business days. For age from a date of birth, use the Age Calculator.
How are months between two dates counted?+
By complete calendar months. The day of the month has to come around again before another month is added. Total months is those months plus 12 for each complete year, not the day count divided by 30.
What does Include end date do?+
It counts the end date as one extra day. From 1 January to 10 January is 9 days with the option off and 10 days with it on. Business days follow the same choice.
How are business days calculated?+
Monday through Friday only. Saturdays and Sundays are skipped. Public holidays are not removed, because this page does not use a holiday calendar.
What if the end date is before the start date?+
The span is the same either way, so the calculator still shows years, months, weeks and days. Use Swap dates to put the fields in order.
Does this include leap years?+
Yes. February 29 is a real calendar day, so total days follow the actual calendar between the two dates.
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