Free online tool
Free Online Unix Timestamp Converter
Convert Unix timestamps to human-readable dates and back. Auto-detects seconds vs milliseconds. Shows UTC, local browser time, and any IANA timezone. Now button inserts the current timestamp. 100% client-side.
01How it works
Enter a timestamp or date
Paste a Unix epoch (seconds or ms) or an ISO 8601 date string. The tool detects the format automatically.
Read the three representations
UTC ISO 8601, your local browser time, and the time in any IANA timezone you select are shown instantly.
Copy any row
Each of the three output rows has its own Copy button. Click to copy that representation to your clipboard.
FAQ
Frequently asked questions
How does the tool decide whether a number is seconds or milliseconds?
Timestamps below 100,000,000,000 (10^11) are treated as seconds since the Unix epoch; above that threshold they are treated as milliseconds. This threshold is April 2286 in seconds, well beyond any realistic future timestamp. The vast majority of 10-digit numbers are seconds; 13-digit numbers are milliseconds.
Where does the timezone list come from?
The timezone picker is populated from Intl.supportedValuesOf('timeZone'), which returns the full IANA timezone database built into your browser — typically around 600 zones. Daylight saving transitions are handled automatically by the browser's Intl implementation.
How are daylight saving time transitions handled?
The converter shows both an ISO 8601 UTC string and a formatted string in your selected timezone. DST is handled by the Intl.DateTimeFormat API, which applies the correct offset for the specific instant — not a fixed UTC offset. So 'America/New_York' will correctly show UTC-4 in summer and UTC-5 in winter.
How do I get the current timestamp?
Click the Now button. It inserts the current Unix time in milliseconds into the input field and immediately shows the conversion. The timestamp is a snapshot — it does not tick. Click Now again to refresh it.
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