Date Duration Calculator
Calculate the exact duration between two dates in years, months, weeks, days, hours, and minutes. Find age, deadline, or project duration.
About this calculator
Date Duration Calculator measures the exact time between two moments, including the time of day. The answer comes back in years, months, days, total weeks, hours, minutes and seconds, together with the number of business days in the span.
The quick buttons set common spans in one click: from now to the end of the year, a week from now or to New Year. It is helpful for project planning, counting hours on a contract or finding out how long is left until an event.
How to use it
- Set the start date and time.
- Set the end date and time.
- Or press a quick button such as To Today, Next Week, This Year or To New Year.
- Read the duration in all units.
Calculation
Duration = End − Start. Total hours is the difference in milliseconds divided by 3,600,000. The years, months and days figure uses calendar borrowing. Business days count Monday to Friday and ignore public holidays.
Worked example
10:00 on 8 November 2026 to midnight on 8 December 2026
| Months and days | 1 month, 0 days |
| Total days | 29 |
| Total hours | 710 |
| Total minutes | 42,600 |
| Business days | 20 |
The partial first day is counted as a fraction, which is why the total is 29 days rather than 30.
Tips and common mistakes
- Use datetime fields when the time of day matters, such as shift lengths or SLA windows.
- Business days exclude weekends but not holidays.
- Daylight saving changes can shift the hour count by one in affected time zones.
- For long spans, rely on total days rather than rounded months.
- The quick buttons are relative to now.
Frequently asked questions
How do I calculate the time between two dates and times?
Subtract the start from the end and convert the result to the units you need.
Does it include business days?
Yes, it counts Monday to Friday in the span.
Can I get the answer in hours?
Yes, the total hours are listed.
Does daylight saving affect the result?
It can change the number of hours by one when a clock change falls inside the span.
Can the end be before the start?
The tool expects the end after the start.
Is the data stored?
No.