Date Calculator
Work out how many days lie between two dates, shift a date by days, weeks, months or years, or calculate an exact age. Results update as you type and stay on your device.
Free Runs locally No signup
Choose a valid date to see the result.
Dates are compared in UTC, so daylight saving time never changes the result.
How to use it
1
Pick a mode
Choose the difference, add/subtract or age calculator at the top of the tool.
2
Enter the dates
Select the start and end dates, a date plus an offset, or a date of birth.
3
Read the result
See the calendar difference, total days, weekdays and weekends, or the next birthday.
Why use this tool
Three calculators in one
Date difference, date arithmetic and age share the same page and the same date logic.
Weekday counts
See how many working days and weekend days fall inside the selected range.
Leap years handled
Month ends and 29 February are clamped correctly, so 31 January plus one month is not March.
Frequently asked questions
How is the date difference calculated?
The tool counts full calendar years, then months, then the remaining days, and also shows the total number of days, weeks and weekdays between the two dates. The start date is not included.
Does daylight saving time affect the result?
No. Dates are treated as calendar days and compared in UTC, so a clock change never adds or removes a day.
What happens when a month is shorter?
Adding one month to 31 January gives 28 or 29 February, and 29 February plus one year gives 28 February. Days are clamped to the end of the target month.
How are weekdays counted?
Monday to Friday count as weekdays, Saturday and Sunday as weekend days. The range runs from the start date up to, but not including, the end date.
Is my data sent anywhere?
No. All calculations run in your browser and nothing is uploaded or logged.
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