DateTimeHub - Online Time & Date Tools
Date Add
Date Add / Subtract Calculator: Add or subtract calendar years, months, weeks, days or precise hours, minutes, seconds from any base date/time. Useful for planning deadlines, scheduling reminders, projecting milestone dates, or computing expirations. Handles leap years, month length differences and daylight saving transitions by using calendar logic instead of raw millisecond math.
Choose a base date/time (click the current clock), enter positive values, then toggle between Add / Subtract. The adjusted result refreshes instantly along with a compact summary. You can pause the running clock to freeze a scenario.
Date Add / Subtract FAQs
How do I add days to a date?
Enter the number under Days while in Add mode. The Adjusted panel shows the resulting date/time immediately.
Can I subtract months safely?
Yes. Switch to Subtract mode. Month length rollover (e.g. Jan 31 minus 1 month) clamps intelligently to the last valid day.
Does it account for leap years?
Leap days are respected. Adding a year to Feb 29 lands on Feb 28 if the target year is not a leap year.
Why pause the running clock?
Pausing freezes the base timestamp so your adjustments don't drift while planning longer spans.
What if I need only weeks?
You can mix fields; weeks convert to 7-day blocks before days are applied.
Related Tools
- Date Difference Calculator – find elapsed time between two dates.
- Time Zone Converter – convert a specific time between zones.
- Countdown Timers – schedule countdowns to target dates.