Unix timestamp converter — epoch to date and back
Convert Unix timestamps to readable dates and back. Seconds, milliseconds, microseconds and nanoseconds are detected automatically, with the current epoch time ticking live.
Runs entirely in your browser — nothing is uploaded.
Seconds, milliseconds, microseconds or nanoseconds — detected automatically.
Date → timestamp
All processing happens in your browser. Your file is never uploaded.
Unix time counts seconds since 00:00:00 UTC on 1 January 1970, ignoring leap seconds. The unit is detected from magnitude: ten digits reads as seconds (valid until the year 5138), thirteen as milliseconds — the format JavaScript uses — sixteen as microseconds and nineteen as nanoseconds. Negative values are moments before 1970. The famous 32-bit overflow lands on 19 January 2038, but only affects systems still storing the count in a signed 32-bit integer.
How to use
- Paste a timestamp. The unit is detected from its size — ten digits reads as seconds, thirteen as milliseconds.
- Read the conversions. ISO 8601, UTC, your local time and a relative description, side by side.
- Go the other way. Enter a date and time to get its epoch value, in UTC or local time.
Questions
What is Unix time?
The number of seconds since 00:00:00 UTC on 1 January 1970 — the epoch. It is the standard internal clock of computing: databases, APIs, log files and JWTs all carry moments as one number, free of time zones and formats. The number is the same everywhere on Earth at any given moment; only its rendering as a local time differs.
How do I know if a timestamp is seconds or milliseconds?
By size. Current time is about 1.75 billion in seconds (10 digits) and 1.75 trillion in milliseconds (13 digits). This tool detects the unit that way, and tells you which it assumed. A 10-digit value read as milliseconds lands in January 1970 — the classic symptom of unit confusion.
What is the year 2038 problem?
Systems storing Unix time in a signed 32-bit integer overflow on 19 January 2038 at 03:14:07 UTC, wrapping to 1901. Modern systems use 64 bits and are fine for 292 billion years; the risk lives in old embedded devices and legacy file formats.
Does Unix time include leap seconds?
No — by definition every Unix day is exactly 86,400 seconds, and leap seconds are absorbed by repeating or smearing a second. Two real-world instants a leap second apart can map to the same Unix time. For timekeeping this matters to almost nobody; for sub-second scientific comparisons across leap-second boundaries it does.
Why does the reverse conversion offer UTC and local?
Because "2026-07-26 12:00" is not a moment until you say where. Ticking "treat as UTC" reads the fields as UTC; unticking reads them in your device’s time zone. The one-hour surprises around daylight-saving changes come precisely from skipping this question.