Unix Timestamp / Epoch Converter
Two-way epoch converter. Seconds or milliseconds, local + UTC + ISO, live clock. Local only.
Timestamp to date
Date to timestamp
What this tool does
Converts between Unix timestamps (epoch time) and human-readable dates, in both
directions, entirely in your browser. Enter a timestamp in seconds or milliseconds and
read it back as local time, UTC, an ISO 8601 string, and a relative phrase like
"3 days ago". Or pick a date and time and get its epoch value in both seconds and
milliseconds. Nothing is sent anywhere; the conversions use your browser's built-in
Date and Intl features.
How to use it
To decode a number, type or paste it into the timestamp box. Leave the unit on
Auto to let the tool guess seconds or milliseconds by digit count, or
pick Seconds or Milliseconds to force it. The four
outputs update as you type, and each has a Copy button. The
Now button fills the current timestamp and keeps it ticking every
second until you edit a field. To go the other way, set the date-and-time picker in the
lower panel and read the epoch seconds and milliseconds. Example: the timestamp
1700000000 in seconds is 2023-11-14T22:13:20.000Z.
Common use cases
- Debugging log lines and API responses that print raw epoch numbers.
- Reading JWT
exp,iat, andnbfclaims, which are Unix timestamps in seconds. - Setting or checking an expiry value for a token, cookie, or cache entry.
- Inspecting database columns stored as epoch integers.
- Turning a chosen date into the timestamp a script or scheduled job expects.
Common pitfalls
- Seconds versus milliseconds. Mixing the two is off by a factor of 1000. A millisecond value read as seconds lands tens of thousands of years in the future; a seconds value read as milliseconds lands in early 1970. If the date looks absurd, flip the unit toggle.
- Timestamps carry no time zone. The number is always UTC based. The zone is applied only when you display it, so the same timestamp is a different wall-clock time for every viewer. Store a zone separately if you need to remember it.
- The date picker uses your local zone. The lower panel reads the date-and-time you enter as local time, then reports the matching epoch value. Two people in different zones entering the same clock time get different timestamps.
- Before 1970 and the year 2038. Dates before 1 January 1970 produce negative timestamps, which some systems reject. Legacy 32-bit systems also overflow on 19 January 2038. This tool handles both, but the system you feed the value to might not.
Frequently asked questions
- What is a Unix timestamp?
- A Unix timestamp, also called epoch time or Unix time, is the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970, not counting leap seconds. It is a single integer that represents one exact moment, independent of any time zone. Databases, log files, APIs, and programming languages store and exchange time this way because integers are compact and easy to compare and sort.
- What is the difference between seconds and milliseconds?
- Classic Unix time counts whole seconds, so a current value has 10 digits (for example 1700000000). JavaScript, Java, and many web APIs count milliseconds instead, so the same moment has 13 digits (1700000000000). This converter auto-detects the unit by digit count: a value with 12 or more digits is treated as milliseconds, otherwise as seconds. You can override the guess with the Seconds or Milliseconds toggle.
- How do I convert a Unix timestamp to a readable date?
- Paste the number into the timestamp box. The tool shows the same instant four ways: your local time with its zone, UTC, an ISO 8601 string, and a relative phrase such as "3 days ago". Every output has a Copy button. If the number is not a valid timestamp, an inline message explains the problem instead of showing a broken result.
- Why does the converted time not match my clock?
- A timestamp is an absolute instant, but the same instant is a different wall-clock time in every zone. The Local time output uses your device zone, while UTC shows the same instant at zero offset. If the two differ by several hours, that gap is your time zone offset, not an error. Confirm your device clock and zone are correct if the local value still looks wrong.
- Does a Unix timestamp store the time zone?
- No. A timestamp is always measured against UTC and carries no zone information at all. To display it for a person you apply a zone at read time, which is why the same number can appear as 2 PM in London and 9 AM in New York. If you need to preserve a specific zone, store it separately alongside the timestamp.
- What is the Year 2038 problem?
- Systems that store Unix time in a signed 32-bit integer can only count up to 2147483647 seconds, which is reached at 03:14:07 UTC on 19 January 2038. One second later the counter overflows and wraps to a negative number, misreading the date as December 1901. Modern systems use 64-bit integers, which push the limit far into the future, so this tool converts dates well beyond 2038.
- What is ISO 8601 format?
- ISO 8601 is an international standard for writing dates and times as text, for example 2023-11-14T22:13:20.000Z. The letter T separates the date from the time and a trailing Z means UTC (zero offset). Because the fields run from largest to smallest, ISO 8601 strings sort correctly as plain text, which makes them a common choice for logs, filenames, and JSON payloads.
Cite this tool
For academic, journalistic, or technical references. Pick a format:
Citations use 2026 as the publication year. Access date is left as a fillable placeholder where the citation style expects one.