Epoch Time Converter
Convert Unix epoch timestamps in seconds and milliseconds to UTC and local human-readable date-time formats.
ISO 8601: 2026-09-05T10:23:19.000Z
9/5/2026, 10:23:19 AM
in seconds
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What Is a Epoch Time Converter?
An epoch time converter translates Unix epoch timestamps (the total number of seconds elapsed since midnight UTC on January 1, 1970, excluding leap seconds) into human-readable calendar dates and times, and vice versa. It is an essential utility for software engineers, database administrators, and IT professionals.
How to Use This Calculator
- Enter any Unix timestamp (in 10-digit seconds or 13-digit milliseconds).
- Click "Use Current Time" to inspect the current timestamp.
- View the decoded UTC date and time, ISO 8601 string, local device timezone, and relative age.
Epoch Transformation Formula
t_{\text{date}} = \text{EpochStart (1970-01-01T00:00:00Z)} + (S_{\text{epoch}} \cdot 1000\text{ ms})Converts scalar seconds since the POSIX epoch baseline into calendar components according to ISO 8601 Gregorian rules.
Worked Example
Scenario: Decode the milestone Unix timestamp 1,000,000,000 (1 billion seconds).
Timestamp: 1,000,000,000 seconds.
Divide by 86,400: ~11,574 days past Jan 1, 1970.
Decodes to: Sunday, September 9, 2001 at 01:46:40 UTC.
Tips & Key Notes
- 10-digit timestamps represent seconds (standard Unix/Linux `time_t`); 13-digit timestamps represent milliseconds (JavaScript `Date.now()`).
- Epoch time is completely timezone-agnostic; it represents the identical instant globally.
- Timestamps prior to 1970 are represented by negative integer values.
Frequently Asked Questions
What is Unix Epoch time?
Unix Epoch time is the count of seconds that have elapsed since January 1, 1970, 00:00:00 UTC (not counting leap seconds).
How do you tell if an epoch timestamp is seconds or milliseconds?
A timestamp in seconds currently has 10 digits (e.g. 1740000000), while a timestamp in milliseconds has 13 digits (e.g. 1740000000000).
Why was January 1, 1970 chosen as the Epoch?
Early Unix engineers chose midnight on January 1, 1970 as an arbitrary, convenient reference point near the creation of the Unix operating system.
Can epoch timestamps be negative?
Yes, negative Unix timestamps represent dates and times before January 1, 1970.
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