Unix Timestamp Converter
Convert timestamps to readable dates and reverse-convert date-time values.
Input
Conversion Output
When to Use Unix Timestamp Conversion
Unix timestamps are compact numeric time values used in APIs, logs, databases, analytics exports, and event pipelines. They avoid many display-timezone problems because the stored value represents one instant, while the readable display can be rendered in UTC or local time.
This converter is useful when you need to inspect a raw timestamp from a log, verify whether a value is seconds or milliseconds, or create a timestamp for a test request. For durable records, keep the UTC value alongside any local-time interpretation.
What Is a Unix Timestamp?
A Unix timestamp counts elapsed time from the Unix epoch: January 1, 1970 at 00:00:00 UTC. Many APIs store it as seconds, while JavaScript date values often use milliseconds.
Seconds vs Milliseconds
Ten-digit values are usually Unix seconds. Thirteen-digit values are usually milliseconds. Mixing the two formats can move a date by decades, so the interpreted unit is shown in the output.
Unix Timestamp Method Table
| Step | Method | Use |
|---|---|---|
| Timestamp input | Numeric values below 1e12 are treated as seconds; larger values are treated as milliseconds. | Use this for API logs, webhook payloads, database fields, and monitoring events. |
| UTC output | The converter returns ISO UTC and UTC string values from the same instant. | Use UTC output when comparing events across services, servers, and time zones. |
| Local output | The browser local date string is shown separately from UTC. | Use local output for quick human review, but keep UTC for durable records. |
| Reverse conversion | A date-time input is converted back into Unix seconds and milliseconds. | Use this when creating test fixtures, API requests, or scheduled job timestamps. |
Reference: The Open Group Base Definitions, General Concepts.
FAQ
Does this support seconds and milliseconds?
Yes. Inputs below 1e12 are treated as seconds. Larger inputs are treated as milliseconds.
Can I reverse-convert date-time to Unix?
Yes. Use the date-time input to get both Unix seconds and milliseconds.
Which timezone formats are shown?
Output includes ISO UTC, UTC string, and browser local time.
Is this useful for backend logs?
Yes. It is ideal for decoding event times in logs, traces, and webhook payloads.
Is conversion local only?
Yes. All conversion runs in your browser with no upload.
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About This Calculator
Convert Unix timestamps to UTC and local date strings, then convert date-time input back to seconds and milliseconds for API debugging, logs, and monitoring workflows.
Frequently Asked Questions
Does this support seconds and milliseconds?
Yes. Inputs below 1e12 are treated as seconds. Larger inputs are treated as milliseconds.
Can I reverse-convert date-time to Unix?
Yes. Use the date-time input to get both Unix seconds and milliseconds.
Which timezone formats are shown?
Output includes ISO UTC, UTC string, and browser local time.
Is this useful for backend logs?
Yes. It is ideal for decoding event times in logs, traces, and webhook payloads.
Is conversion local only?
Yes. All conversion runs in your browser with no upload.
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