Unix Timestamp Converter: Epoch to Date and Back
Convert Unix epoch timestamps to human-readable dates and convert dates back to timestamps. Auto-detects seconds and milliseconds, and shows UTC, ISO 8601, local, and relative time. Free and 100% in your browser.
Timestamp to Date
Supports Unix timestamps in seconds, milliseconds, and microseconds.
Date to Timestamp
Enter a timestamp or date to see results
TimeZone Support
Instantly view converted dates in both UTC and your local timezone.
Relative Time
See human-friendly relative time formats like '2 hours ago' or 'in 5 days'.
Date to Timestamp
Easily convert any calendar date back into a Unix timestamp.
Real-time Epoch
Always see the current live Unix timestamp at the top of the tool.
Unix Timestamp Converter: Epoch to Date, and Date to Epoch
A Unix timestamp converter turns an epoch value — the count of seconds since 1970-01-01T00:00:00 UTC — into a readable date, and turns a date back into a timestamp. Paste a number to get UTC, ISO 8601, local time, and a relative phrase; pick a date to get the epoch. It auto-detects seconds vs milliseconds and runs 100% in your browser, free, with no upload.
How to convert a Unix timestamp to a date
- Read the live Current Unix Epoch Time ticker at the top — press Pause to freeze it for copying.
- In the Timestamp to Date card, type or paste an epoch value (seconds, milliseconds, or microseconds), then press Convert.
- Read the four outputs: Unix Timestamp, UTC Date, Local Date, and a Relative phrase such as "2 hours ago".
- To go the other way, use the Date to Timestamp card, pick a date and time, and press Convert — the input is read in your local timezone.
- Click the copy icon next to any field to send that value to your clipboard. Leave the input empty and press Convert to use the current epoch.
What is Unix epoch time, and how does it work?
Unix time is the number of non-leap seconds that have passed since the Unix epoch, 00:00:00 UTC on January 1, 1970. The value is a single integer, which makes it trivial to store, sort, and subtract. Because it is anchored to UTC, one timestamp names the same instant everywhere on Earth — timezone is only applied when you display it.
A detail most converters skip: by the POSIX definition, "each and every day shall be accounted for by exactly 86,400 seconds." That means Unix time deliberately ignores leap seconds, so it trades astronomical exactness for clean arithmetic. This tool converts using the JavaScript Date object: new Date(seconds * 1000) for epoch→date and Math.floor(date.getTime() / 1000) for date→epoch, then formats with toISOString() (ISO 8601), toUTCString() (UTC), and toLocaleString() (local). For the date and time format spec itself, see the ISO 8601 standard.
Worked examples: input → output
Epoch seconds → date
1700000000 → UTC: Tue, 14 Nov 2023 22:13:20 GMT · ISO: 2023-11-14T22:13:20.000Z
Milliseconds → date
1700000000000 → same instant; the 13-character input is read as milliseconds, not seconds.
The epoch zero point
0 → UTC: Thu, 01 Jan 1970 00:00:00 GMT
Edge case · Year 2038 overflow
Convert 2147483647 and you get 2038-01-19 03:14:07 UTC — the largest value a signed 32-bit timestamp can hold. The very next second overflows on 32-bit systems and is misread as 1901-12-13 20:45:52 UTC. This tool uses 64-bit JavaScript numbers, so it keeps converting correctly far past 2038.
Epoch reference values
Common epoch milestones and the exact second-counts behind everyday durations. The duration values are precise because Unix time treats every day as exactly 86,400 seconds.
| Unix value | UTC date / meaning | Notes |
|---|---|---|
| 0 | 1970-01-01 00:00:00 | The Unix epoch (start) |
| 3,600 | 1 hour | Common session / token TTL |
| 86,400 | 1 day | Always exactly 86,400 s (POSIX) |
| 604,800 | 1 week | 7 × 86,400 |
| 1,000,000,000 | 2001-09-09 01:46:40 | The "Giga-epoch" milestone |
| 2,147,483,647 | 2038-01-19 03:14:07 | Max signed 32-bit timestamp (Y2K38) |
The seconds-vs-milliseconds rule this tool actually uses
Most explanations say "10 digits is seconds, 13 digits is milliseconds." Under the hood this converter is stricter and simpler: it switches to milliseconds when the input string is longer than 11 characters (timestamp.toString().length > 11), otherwise it treats the value as seconds and multiplies by 1000. So an 11-digit second value still reads as seconds, while a 12-digit value already flips to milliseconds.
The practical gotcha: that length test counts every character, including a leading minus sign. A negative pre-1970 timestamp like -1000000000 is 11 characters, so it stays in seconds — but pad it and the count can tip it into milliseconds. When in doubt, normalize to a clean integer first, or paste the millisecond value and let the tool detect it.
Runs 100% in your browser
Your data never leaves your device. Every conversion runs locally with the JavaScript Date object, and the live epoch ticker updates once per second from your own system clock — no uploads, nothing leaves your device. I tested the seconds path (10-digit), the millisecond path (13-digit), the 0 epoch, and the 2147483647 Year-2038 boundary, plus the Date-to-Timestamp card, which reads the datetime-local picker in local time. Relative phrasing comes from the native Intl.RelativeTimeFormat, switching from seconds to minutes, hours, days, months, then years as the gap grows.
Frequently asked questions
Is this Unix timestamp converter free?
Yes — 100% free with no signup and no usage cap. Both conversion directions, the live ticker, and copy-to-clipboard are fully available.
Does my data get uploaded anywhere?
No. All conversion runs in your browser with JavaScript, so no timestamp or date you enter is sent to a server. The tool keeps working offline once the page loads.
Are Unix timestamps timezone-independent?
Yes. A timestamp is an absolute count of seconds tied to UTC, so the same value means the same instant everywhere. The tool then displays it as UTC, ISO 8601, your local time, and a relative phrase. For switching wall-clock between regions, use the timezone converter.
What happens in the Year 2038?
At 03:14:07 UTC on January 19, 2038 a signed 32-bit timestamp hits its maximum of 2,147,483,647 and the next second overflows to a value legacy systems read as 1901. 64-bit systems — and this tool — are unaffected. Read the deep dive in our Unix timestamp and epoch guide.
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Guide: Unix Timestamps & EpochHow epoch time, leap seconds & Y2K38 work
Last updated: June 2, 2026 · Runs 100% in your browser — no uploads, nothing leaves your device.
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