What is a Unix Timestamp?
A Unix timestamp — also called epoch time or POSIX time — is a single integer that represents a point in time as the number of seconds elapsed since the Unix Epoch: January 1, 1970, at exactly 00:00:00 UTC. Because it is a simple integer with no timezone or locale information embedded, it is the most portable and unambiguous way to store and exchange dates in software.
You will encounter Unix timestamps in server logs, database records, API responses, JSON payloads, JWT tokens, HTTP headers, file system metadata, and configuration files. Any time you see a large number like 1717761600 or 1717761600000 next to a date field, you are looking at a Unix timestamp.
Seconds vs. Milliseconds
The original Unix specification defines epoch time in seconds, but JavaScript’s Date object and many modern APIs (including browsers, Node.js, Java’s System.currentTimeMillis(), and Python’s time.time_ns()) work in milliseconds. This creates a common source of confusion: the same moment in time is represented as 1717761600 in seconds and 1717761600000 in milliseconds.
This tool automatically detects which unit you are using. Values greater than 100,000,000,000 (roughly year 5138 in seconds) are treated as milliseconds. Everything at or below that threshold is treated as seconds. You never need to specify the unit manually.
How to Convert a Unix Timestamp to a Human-Readable Date
- Paste or type your timestamp into the Timestamp → Date tab.
- The tool instantly shows the equivalent date in multiple formats: Unix seconds, Unix milliseconds, ISO 8601, a formatted local time, and relative time.
- Click Copy next to any row to copy that value to your clipboard.
- Click Use Current Time to load the current moment as a starting point.
How to Convert a Date to a Unix Timestamp
- Switch to the Date → Timestamp tab.
- Enter a date in ISO 8601 format, such as
2024-06-07T12:00:00Z, or just a date like2024-06-07. - The tool returns the corresponding Unix timestamps in both seconds and milliseconds.
ISO 8601 Format Reference
ISO 8601 is the international standard for representing dates and times. The most common forms are:
| Format | Example | Notes |
|---|---|---|
| Date only | 2024-06-07 | Midnight UTC assumed |
| Date + time (UTC) | 2024-06-07T12:00:00Z | Z = UTC |
| Date + time (offset) | 2024-06-07T14:00:00+02:00 | Local time with offset |
| Date + time (no tz) | 2024-06-07T12:00:00 | Interpreted as local time |
When working with APIs and databases, always prefer the UTC format with the Z suffix to avoid ambiguity.
Common Unix Timestamps for Reference
| Moment | Unix (seconds) | ISO 8601 |
|---|---|---|
| Unix Epoch | 0 | 1970-01-01T00:00:00Z |
| Y2K | 946684800 | 2000-01-01T00:00:00Z |
| Year 2024 start | 1704067200 | 2024-01-01T00:00:00Z |
| Year 2038 problem | 2147483647 | 2038-01-19T03:14:07Z |
| Year 3000 | 32503680000 | 3000-01-01T00:00:00Z |
The Year 2038 problem (also called Y2K38) occurs because 32-bit signed integers overflow at 2147483647. Systems using 32-bit timestamps will wrap around to negative values on January 19, 2038. Modern 64-bit systems are not affected.
Timezones and UTC
Unix timestamps are always in UTC. When displaying timestamps as human-readable dates, a timezone must be chosen. This tool uses your browser’s local timezone by default (Intl.DateTimeFormat().resolvedOptions().timeZone), which gives you the most useful result in everyday use.
If you need to compare timestamps across timezones, always convert to ISO 8601 with a UTC offset or Z suffix first.
Privacy
All conversions run entirely in your browser using built-in JavaScript APIs. No data is sent to any server. This tool works offline once the page has loaded.