Unix Timestamp Converter
Convert a Unix timestamp to a readable date, or a date back to a timestamp, in seconds and milliseconds.
How to use this tool
- Fill in the options above.
- The result updates as you change the input — there is nothing to submit and nothing to wait for.
- Read the figures in the result panel.
- Use Copy or Download if you need the output elsewhere. Nothing was uploaded at any point.
Ten-digit input is read as seconds and thirteen-digit as milliseconds, which is the usual source of confusion when a timestamp comes back a thousand times too large or small. Leave the field empty and you get the current time in both units.
Unix Timestamp Converter — the specification
| Input | Unix seconds, Unix milliseconds, or a date string |
|---|---|
| Output | Seconds, milliseconds, ISO 8601, UTC and local |
| Extras | Day of week and a relative description |
| Empty input | Shows the current time |
How it works
This tool runs entirely in your browser. There is no server involved, which means nothing you type or upload is transmitted, stored, or logged — and there are no usage limits, because there is nothing for us to ration.
You can confirm it yourself: open your browser's developer tools, select the Network tab, and use the tool. No request is made.
Who needs Unix Timestamp Converter
Reading a timestamp out of a log file, checking when a token expires, or converting a date into the format an API expects.
Unix Timestamp Converter — frequently asked questions
Seconds or milliseconds?
Unix time is defined in seconds, and that is what most APIs and databases use. JavaScript’s Date.now() returns milliseconds, which is why the two get mixed up. Ten digits is seconds; thirteen is milliseconds.
Why does local time differ from UTC here?
Local time uses your device’s timezone and daylight saving rules. UTC has neither. For anything stored or transmitted, use UTC.
What is the 2038 problem?
Systems storing Unix time in a signed 32-bit integer overflow on 19 January 2038. Anything modern uses 64-bit, but old embedded systems and file formats can still hit it.
Does this work offline?
Yes. Once the page has loaded you can disconnect from the internet and it keeps working, because all the processing happens in your browser. That is also the simplest way to confirm nothing is being sent anywhere.
Is there a limit on how much I can paste in?
Nothing we impose. The practical limit is your device’s memory, since the work happens locally. Very large inputs get slower rather than being refused.
Can I use this on a phone?
Yes. The layout adapts to a small screen and everything works the same way.
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Background reading: Text and Developer Tools That Never Upload Your Data
Your file never leaves your device. Open your browser's Network tab while you use this page and you will see no upload — how that works.
Disclaimer. Published requirements change without notice. Confirm against the official source before you submit. Full disclaimer.