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What Is a Unix Timestamp?
A Unix timestamp (also called epoch time or POSIX time) is the number of seconds that have elapsed since January 1, 1970 00:00:00 UTC. It is the most common way to store and transmit date and time information in software because it is a single integer, timezone-independent, and easy to compare and sort.
Most programming languages, databases, and APIs use Unix timestamps internally. JavaScript Date.now() returns milliseconds since the epoch. Python time.time() returns seconds. MySQL TIMESTAMP columns store seconds since epoch. AWS Lambda logs, JWT expiry fields, and virtually every event-driven system uses Unix timestamps.
The current Unix timestamp is always increasing. The value 0 corresponds to January 1, 1970. The value 1000000000 (one billion) corresponded to September 9, 2001. The value 2147483647 is the 32-bit signed integer maximum, corresponding to January 19, 2038 — the date of the famous Year 2038 problem for systems that store timestamps as 32-bit signed integers.
- Seconds since January 1, 1970 00:00:00 UTC
- Timezone-independent — the same number everywhere on Earth
- Millisecond timestamps: multiply seconds by 1000 (JavaScript Date.now() format)
- Year 2038 problem: 32-bit signed integer limit reached at 2147483647
How to Use This Unix Timestamp Converter
To convert epoch to date: paste a Unix timestamp (seconds or milliseconds) into the top field and the tool shows the equivalent date and time in UTC and your local timezone. To convert date to epoch: use the date/time picker in the bottom section and the tool returns the corresponding Unix timestamp.
The tool automatically detects whether the input is in seconds or milliseconds based on the number of digits. A 10-digit number is treated as seconds; a 13-digit number is treated as milliseconds.
Common Unix Timestamp Values to Know
A handful of milestone timestamps are useful to know for quick sanity checks. The year 2000 started at epoch 946684800. The year 2020 started at 1577836800. A billion seconds after epoch (September 9, 2001) was a notable milestone. The maximum 32-bit signed integer epoch (2147483647) corresponds to January 19, 2038 at 03:14:07 UTC.
For JWT expiry debugging, a common pattern is exp: now + 3600 (one hour) or now + 86400 (one day). The number 86400 is the number of seconds in a day, which is a useful constant to memorize when working with time-based APIs.
- 0 = January 1, 1970 00:00:00 UTC
- 946684800 = January 1, 2000 (Y2K)
- 1577836800 = January 1, 2020
- 1700000000 = November 14, 2023
- 2147483647 = January 19, 2038 (32-bit max)
- 86400 = seconds in one day; 3600 = seconds in one hour
Why marketers use this tool
- Convert Unix epoch timestamps to readable dates without mental math
- Convert any date and time back to a Unix timestamp for API calls
- See timestamps in UTC and local time simultaneously
Frequently Asked Questions
What is a Unix timestamp?
A Unix timestamp is the number of seconds since January 1, 1970 00:00:00 UTC. It is a timezone-independent integer used by virtually all operating systems, databases, and APIs to store date and time information. A 10-digit number is a seconds-based Unix timestamp; a 13-digit number is usually milliseconds.
What is the current Unix timestamp?
The current Unix timestamp changes every second. Use this converter to see the current epoch value, or run Date.now() / 1000 in a browser console (JavaScript), time.time() in Python, or System.currentTimeMillis() / 1000 in Java.
Why is my Unix timestamp 13 digits?
A 13-digit Unix timestamp is in milliseconds, not seconds. JavaScript uses milliseconds (Date.now() returns a 13-digit number). Divide by 1000 to get the seconds-based timestamp that most other systems use.
What is the Year 2038 problem?
Systems that store Unix timestamps as a 32-bit signed integer can only represent values up to 2147483647, which corresponds to January 19, 2038 at 03:14:07 UTC. After that second, the counter overflows to a large negative number. Modern systems use 64-bit integers, which extend the range far beyond any practical limit.
Can I convert a UTC date to a Unix timestamp?
Yes. Use the date-to-epoch section of this converter. Select a date and time in UTC and the tool returns the corresponding Unix timestamp. Alternatively, in Python use calendar.timegm(datetime.utctimetuple()), or in JavaScript use Date.UTC() divided by 1000.