Understand timestamps across timezones
A Unix timestamp counts time from January 1, 1970 at midnight UTC. Many systems store seconds; browser APIs commonly use milliseconds. Confusing those units can produce a date near 1970 or far in the future. This converter accepts both and shows the interpreted instant as Unix seconds, Unix milliseconds, an ISO string, and a readable date in your selected timezone. With the input empty, it displays the current time and updates every second.
Paste a timestamp or a date into the input field. Auto-detection treats numeric magnitudes of at least 100 billion as milliseconds and smaller values as seconds. That is a practical heuristic, not a universal rule. For old millisecond timestamps or very distant second timestamps, use the unit selector to state your intention explicitly. Negative Unix values represent instants before the epoch. Fractional seconds can describe subsecond timing.
ISO dates with an offset are the clearest way to exchange a moment in time. For example, 2026-09-26T12:00:00Z identifies noon UTC. The final Z means UTC, while an offset such as +05:30 describes the difference from UTC. A date-time without an offset is interpreted using your browser timezone. Date-only ISO input is interpreted as UTC. Human date text is supported through the browser parser, whose handling of ambiguous regional formats can differ.
Choose a display timezone to see the same instant in another place. This changes the presentation, not the Unix timestamp. Named timezones account for daylight-saving rules available in the browser. Clock changes can cause local times to repeat or disappear, so include an explicit offset when entering a time near a daylight-saving transition. Copy the ISO result when sharing a timestamp with another person or service. For scheduling or historical work, confirm the intended timezone and the rules applicable to your date.
Frequently asked questions
Does changing the timezone change the instant?
No. It changes the calendar and clock representation of the same moment.
Why is my input shown near 1970?
You may have supplied seconds where milliseconds were expected, or selected the wrong numeric unit.
Can I use day/month/year?
Ambiguous regional input is unreliable across browsers. Prefer an ISO date with an explicit offset.