About this tool
Someone says "that was 36 hours ago" and you need a day and a time; a log shows a timestamp and you need to know how stale it is. This calculator does both: enter any mix of days, hours, minutes, and seconds to get the exact date and clock time that far in the past or the future, or enter a date and time to get the elapsed duration in years, months, days, hours, minutes, and seconds.
Results are in your local time zone with UTC, ISO 8601, and Unix timestamp versions for logs and code, and the clock keeps running so the answer is always current.
How to use it
- Choose whether you want a time in the past, a time in the future, or the time since a date.
- Enter the days, hours, minutes, and seconds (or pick the date and time).
- The answer updates every second with the current time.
Questions
What day was it 48 hours ago?
Two days before today at the same clock time; the calculator names the weekday and date so you do not have to count back across a month boundary.
Does it handle daylight saving time?
Yes. The arithmetic is done on absolute time, then shown in your local zone, so an interval that crosses a clock change comes out correct even though the wall-clock difference is not a round number.
Is anything I type sent anywhere?
No. The calculator runs entirely in your browser; nothing is stored or transmitted. Refresh the page and it starts clean.
Is it free, are files uploaded, which browsers work: the general questions are answered once for the whole site.