Unix Timestamp Converter
Timestamp to date
Max 64 bytes · Seconds or milliseconds, auto-detected · Converts automatically as you type
Date to timestamp
Interpreted in your browser's local timezone
A Unix timestamp (also called epoch time or POSIX time) is a single number representing a point in time: the number of seconds — or, in many programming environments, milliseconds — that have elapsed since 1970-01-01T00:00:00 UTC, the “Unix epoch.” Because it’s just one number with no embedded timezone or calendar formatting, it’s the most common way computers store and exchange points in time internally — in databases, log files, API responses, JSON Web Tokens, and file metadata.
That same simplicity is what makes timestamps hard to read at a glance. 1753452730 is unambiguous to a computer but tells a person nothing without a conversion step — and that step has a common trap: whether the number is in seconds or milliseconds. A timestamp in milliseconds is exactly 1,000 times larger than the same instant in seconds, so treating one as the other doesn’t produce an error, it silently produces a wildly wrong date (usually decades off). This tool auto-detects the unit by digit count — 10 digits reads as seconds, 13 as milliseconds, matching the ranges in common use today — but never guesses silently past your intent: the unit toggle always overrides auto-detection when set explicitly.
Converting a timestamp to a date only gets you halfway to being useful, though, because “a date” isn’t one fixed thing — it depends on which timezone you’re reading it in. This tool shows a timestamp’s UTC representation, your browser’s resolved local timezone (named explicitly, not just as an offset), and the ISO 8601 form all at once, specifically so they can be compared side by side rather than looked up one at a time. The reverse direction works the same way in reverse: enter a date and time in your local timezone, and get back both the seconds and milliseconds forms of its Unix timestamp, ready to paste into whichever system expects which unit.
All conversion happens locally using the browser’s built-in Date and Intl.DateTimeFormat APIs — including timezone and daylight-saving-time resolution, which those APIs handle correctly without needing an external timezone database. Nothing you enter is sent anywhere.
Examples
- Reading a JWT's exp claim — the JWT Decoder tool shows a token's exp, iat, and nbf fields as raw Unix timestamps; paste one in here to see exactly when it expires in your own timezone.
- Converting a server log timestamp — logs are almost always recorded in UTC or as a raw epoch value; convert one to your local time to line it up with when you actually noticed the incident.
- Comparing a meeting time across timezones — convert a local date and time to its Unix timestamp, then read that same timestamp back to see what it corresponds to in UTC or paste it into another tool that expects local time in a different zone.
Frequently asked questions
Should I use seconds or milliseconds?
date +%s) use whole seconds since the epoch. JavaScript's Date.now() and most browser and Node.js APIs use milliseconds. This tool auto-detects which one you've pasted by digit count — a 10-digit number is read as seconds, a 13-digit number as milliseconds — but you can force either interpretation with the unit toggle if a value is ambiguous.What is "the epoch"?
How does this tool handle timezones and daylight saving time?
Intl.DateTimeFormat API, which applies whatever daylight saving rules were in effect for that zone on that specific date. That's why the UTC offset shown can differ for two dates in the same zone a few months apart.