What is a Unix Timestamp?
A Unix timestamp is the number of seconds that have elapsed since January 1, 1970 at 00:00:00 UTC, a moment known as the Unix epoch. It is a simple integer that is easy to compare, sort, and store, which is why it is used pervasively in programming languages, databases, logs, and APIs. Because the value is timezone-independent, it avoids the confusion that often accompanies human-readable date strings. The current Unix timestamp is now well over a billion and continues to grow by one every second.
Converting Timestamps
In JavaScript, use Date.now() to get the current timestamp in milliseconds and divide by 1000 for seconds. Convert a Unix timestamp to a human-readable date with new Date(timestamp * 1000).toISOString(), which always returns UTC, or pass a timezone offset for local display. Many languages provide dedicated helpers: in Python, time.time() returns the current seconds-based timestamp, and datetime.fromtimestamp() converts one to a datetime object. Our Timestamp Converter handles both directions across multiple formats and timezones instantly.
Common Pitfalls
The most frequent bug is mixing seconds and milliseconds: JavaScript and several databases use milliseconds, while most APIs and system tools use seconds, so a value can appear off by roughly a thousand times. Always confirm the unit before parsing an external timestamp. Remember that Unix timestamps are always UTC, so converting to a local timezone without an explicit offset produces incorrect wall-clock times. Also beware of out-of-range values, integer overflow on 32-bit systems for dates after 2038, and timestamps that include a fractional component or are stored as strings with trailing zeros.