Date duration calculator
Calculate days, weeks, full years and months between two calendar dates, for example for age, project duration or deadlines.
Calculate the duration between two dates
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Choose the earlier date as the start date.
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Choose the later date as the end date.
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The result shows total days and the calendar-accurate split into years, months and days.
If you need a bespoke version
You can keep using this free tool as it is. If you need a bespoke version with your own rules, data or workflows for a website, shop or internal process, I can build it for you – for example with custom rules and data sources, approvals and exports, and website or shop integration.
How this tool calculates
Full years and months are counted according to the calendar. Total days are based on the actual difference between the dates.
Your inputs and results remain on your device. Reloading the page restores the default values.
Terms used in this calculation
- Calendar-accurate
- Months and years are counted according to their actual calendar lengths.
- Total days
- The actual number of days between the two dates.
- Duration
- The period from the start date to the end date.
Frequently asked questions
Is the start day included?
The calculator shows the elapsed time between the two date boundaries.
Can I use this to calculate my age?
Yes. Enter your date of birth as the start and the relevant date as the end.