Convert Unix timestamps and timezone-aware wall-clock date-times between epoch seconds, milliseconds, UTC, and IANA time zones.
Time
Convert Unix timestamps into timezone-aware calendar strings, or turn a wall-clock date and time in any IANA zone back into epoch seconds and milliseconds.
Conversion mode
Timezone note
Unix time counts POSIX-style seconds from 1970-01-01 00:00:00 UTC. Leap seconds are not represented as extra Unix seconds, so keep that limitation in mind for specialist timing work.
Also in Time & Duration
Epoch Time
A Unix time converter helps when software timestamps and human-readable calendar strings have to move cleanly between systems. Logs, APIs, databases, schedulers, and debugging tools often store epoch seconds or milliseconds, while humans need readable wall-clock dates in a specific timezone.
Unix time counts POSIX-style seconds from 1970-01-01 00:00:00 UTC, commonly called the Unix epoch. That makes it compact and machine-friendly, which is why it appears in databases, programming languages, APIs, and telemetry systems.
A timestamp by itself does not tell a human much. The same moment has to be rendered in UTC or in a chosen local timezone before it becomes immediately useful for debugging, incident review, scheduling, or data exchange.
Many systems store Unix time in whole seconds, while JavaScript and several browser APIs use milliseconds. A robust converter therefore needs to recognise both scales and normalise them before showing the final result.
The reverse direction is equally important: when you enter a wall-clock date and time, the timezone must be explicit. Noon in UTC is not the same instant as noon in New York or Tokyo, so the page lets you anchor the calendar input to a chosen IANA timezone before it is converted back to epoch time.
Unix milliseconds = Unix seconds × 1,000
Standard relationship between the two common timestamp scales used in APIs and browser code.
Wall-clock time + timezone → UTC instant → Unix time
Conceptual flow for converting a local calendar input into a single epoch value.
POSIX Unix time does not represent leap seconds as extra countable Unix seconds. That is fine for most application logging, scheduling, and web work, but it matters when you are comparing Unix time against specialist timing systems or standards that track leap-second behaviour explicitly.
Timezone conversion also depends on the IANA timezone database because daylight-saving rules and historical offsets change over time. A converter should therefore treat named timezones as rulesets, not just as fixed offsets like UTC+1.
Frequently asked questions
The Unix epoch is 1970-01-01 00:00:00 UTC. Unix timestamps count seconds or milliseconds forward from that instant.
Because they are usually Unix milliseconds rather than Unix seconds. Multiplying seconds by 1,000 gives the millisecond form used by many browser and JavaScript APIs.
Because the same wall-clock reading can represent different instants in different places. 2024-01-15 12:00 in UTC is a different instant from 2024-01-15 12:00 in America/New_York.
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