Timestamp Converter
Convert Unix time to human-readable dates and back — instantly, with auto-detected units.
All conversions happen instantly in your browser using your device’s clock and timezone data — nothing is sent to a server.
What a Unix Timestamp Actually Is
A Unix timestamp (also called epoch time) is simply the number of seconds that have passed since midnight UTC on January 1, 1970 — a fixed reference point computing systems agreed on decades ago. Instead of storing a date as a calendar string, most databases, APIs, and server logs store it as this single, ever-increasing number, which is faster to compare, sort, and do math on than a formatted date string.
Why Developers Constantly Need to Convert It
The catch is that a raw timestamp like 1735689600 is meaningless to a human at a glance. Developers run into this constantly: an API response returns a created_at field as an epoch number, a JWT token’s exp and iat claims are Unix timestamps that need checking against the current time, a server log timestamps every line in epoch seconds, or a database column needs to be sanity-checked against “did this actually happen when I think it did.” Converting back and forth by hand, or writing a throwaway script each time, is exactly the kind of small friction a dedicated tool removes.
The Seconds-vs-Milliseconds Trap
One of the most common bugs around timestamps isn’t a big conceptual error — it’s a units mismatch. Most Unix and Linux tooling works in seconds since the epoch, but JavaScript’s Date.now() and many web APIs return milliseconds since the epoch. Feed a seconds-based timestamp into something expecting milliseconds (or vice versa) and you’ll get a date that’s wildly wrong — often showing sometime in 1970, or thousands of years in the future. This tool auto-detects which unit you’ve pasted in based on the number’s magnitude (a current-era seconds timestamp is 10 digits; the equivalent in milliseconds is 13), and tells you which one it assumed so you can double check.
The Year 2038 Problem
Worth knowing if you work with older systems: many systems historically stored Unix time as a signed 32-bit integer, which can only count up to January 19, 2038, 03:14:07 UTC before it overflows and wraps around to a negative number — effectively jumping back to 1901 from the system’s point of view. Most modern systems have since moved to 64-bit timestamps, which push that limit billions of years out, but the 32-bit issue still shows up in older embedded systems, some file formats, and legacy databases.
How This Tool Works
The converter runs entirely on your device’s built-in JavaScript Date object — the same engine your browser uses for every date calculation on the web — so there’s no server round-trip and no dependency on an external time API. Converting a timestamp to a date shows your local time, UTC time, an ISO 8601 string (the standard format most APIs expect), and a human-readable relative time (“3 days ago”). Converting a date to a timestamp lets you specify whether you’re entering local time or UTC, since that distinction changes the resulting number.
Timestamp Converter — FAQ
Why does my timestamp show the wrong date?
The most common cause is a seconds/milliseconds mismatch — feeding a 10-digit seconds timestamp into code or a tool that expects 13-digit milliseconds (or the reverse) produces a wildly incorrect date, often in 1970 or far in the future. This tool auto-detects which unit you’ve entered based on how many digits it has.
What’s the difference between Unix time in seconds vs. milliseconds?
Both count time since January 1, 1970 UTC, but seconds-based Unix time is the traditional Unix/Linux standard, while JavaScript and many web APIs use milliseconds (seconds × 1000) for finer precision. A current-era seconds timestamp has 10 digits; the same moment in milliseconds has 13.
Is a Unix timestamp the same in every timezone?
Yes — that’s the entire point of it. A Unix timestamp represents one exact, unambiguous instant regardless of timezone; only the human-readable date/time you convert it into changes depending on which timezone you’re displaying it in.
What is the Year 2038 problem?
Systems that store Unix time as a signed 32-bit integer will overflow on January 19, 2038, wrapping around to a negative number that represents a date in 1901. Most modern 64-bit systems aren’t affected, but the issue can still surface in older embedded systems and legacy file formats.
Is my data sent anywhere when I use this converter?
No. All conversion happens locally using your browser’s built-in date engine and your device’s clock and timezone settings. Nothing you enter is transmitted to or stored on a server.