Unix Timestamp Converter
Convert epoch values and ISO dates with explicit units and timezones.
Epoch to date
Date to epoch
Choose a wall-clock date and IANA timezone. Offset changes and daylight-saving transitions are resolved before creating the epoch.
Working notes
Use Unix Timestamp Converter with the boundary visible.
Unix Timestamp Converter translates Unix seconds or milliseconds and ISO date strings with explicit unit selection, UTC output, and chosen timezone context.
What is Unix Timestamp Converter?
A Unix timestamp (also called epoch time or POSIX time) counts the number of seconds that have elapsed since January 1, 1970 at 00:00:00 UTC — a moment known as the Unix epoch. This single integer representation of time is the standard in most programming languages, databases, APIs, and log systems because it is timezone-independent, compact, and trivially comparable. JavaScript uses millisecond timestamps (13 digits), while most backend languages and databases use second timestamps (10 digits). ISO 8601 date strings (like 2024-01-01T00:00:00Z) are the human-readable counterpart, including timezone information. Converting between these formats is a daily task: reading timestamps in database rows, parsing API responses, debugging log entries, and setting expiration times in JWT tokens or cache headers. This tool converts in both directions (epoch to date, date to epoch) with explicit unit selection (seconds vs milliseconds) and displays the result in both UTC and a timezone you choose from the IANA timezone database.
When to use it
- Reading API timestamps — convert a Unix epoch from an API response to a human-readable date to verify expiration times, creation dates, or event timestamps.
- Debugging log entries — convert timestamps in application logs to your local timezone to correlate events with user reports.
- Setting JWT expiration — calculate the epoch value for "30 minutes from now" or "end of day UTC" to set the exp claim in a JWT token.
- Database queries — convert between epoch integers and date strings when writing WHERE clauses or reading query results.
- Comparing timestamps across systems — normalize timestamps from different sources (seconds, milliseconds, ISO strings) to a common format for comparison.
How to use it
- 01Enter a Unix timestamp (seconds or milliseconds) or an ISO 8601 date string.
- 02Select the input unit: seconds (10 digits), milliseconds (13 digits), or auto-detect.
- 03Choose the display timezone from the IANA timezone database.
- 04Review the converted date in both UTC and the selected timezone.
- 05Copy the timestamp or date string in the format you need.
Common mistakes
- Confusing seconds and milliseconds — JavaScript Date.now() returns milliseconds, but most APIs and databases use seconds. A 10-digit number is seconds (valid through year 2286); 13 digits is milliseconds.
- Ignoring timezone when converting dates — "2024-01-15 09:00" could be in any timezone. Without explicit timezone information, the conversion is ambiguous.
- Year 2038 problem — 32-bit signed integers overflow on January 19, 2038. Modern systems use 64-bit timestamps, but legacy systems may still be affected.
- Daylight saving time gaps — some local times do not exist (spring forward) or occur twice (fall back). The converter shows UTC to avoid ambiguity; verify DST handling in your application.
- Negative timestamps — dates before the Unix epoch (January 1, 1970) have negative timestamps. Not all systems handle negative epoch values correctly.
Synthetic example
Convert a Unix second value
Input
1704067200 seconds
Result
2024-01-01T00:00:00.000Z
Related standards
Limits and data boundary
- Ambiguous date strings are rejected rather than guessed.
- Timezone rules can change; confirm future operational schedules in the target system.
Frequently asked questions
- What is a Unix timestamp?
- A Unix timestamp counts the number of seconds (or milliseconds) since January 1, 1970 00:00:00 UTC. It is the standard way to represent time in APIs, databases, and log files.
- How do I tell if a value is seconds or milliseconds?
- A 10-digit number is typically seconds (covers dates through 2286). A 13-digit number is typically milliseconds. This tool lets you choose the unit explicitly.
- Does this tool handle timezones?
- Yes. The converter shows both the UTC time and a localized representation in a timezone you select from the IANA timezone database.
- What is the Year 2038 problem?
- On January 19, 2038, a 32-bit signed Unix timestamp overflows. Systems using 32-bit timestamps will wrap to a negative number, causing date errors. Modern systems use 64-bit timestamps to avoid this.
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