Everyday
Date Calculator
Add, subtract and diff dates.
Result date
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Day of week
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Days
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Weeks
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Months
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FAQ
- How are months calculated in the difference mode?
- The month difference counts whole calendar months between the two dates, then adds the remaining days as a decimal fraction of the average month length (30.44 days). The displayed whole-month count is always an integer.
- What happens when adding months lands on a day that does not exist?
- JavaScript's Date object automatically rolls over — for example, adding 1 month to January 31 gives March 2 (or 3 in a leap year) because February 31 does not exist. This matches common spreadsheet behaviour.
- Is my data sent anywhere?
- No. All calculations run entirely in your browser; no data is uploaded or stored.