1
Magnitude distinguishes seconds from milliseconds
Inputs longer than twelve digits are treated as milliseconds. Shorter values are multiplied by 1,000 before constructing a JavaScript Date.
Unix Timestamp Converter
Convert between Unix timestamps and human-readable dates with timezone support and relative time display.
Tested tool guide
Developer and data tools
Checked July 30, 2026
What Unix Timestamp Converter does, with a checked example
Unix time counts elapsed seconds from 1970-01-01 00:00:00 UTC, apart from the platform treatment of leap seconds. This converter accepts common second and millisecond values, shows several date representations, and can turn a calendar input back into whole Unix seconds.
Worked example
A concrete input and expected output from the current implementation.
Input
0 seconds
Expected output
1970-01-01 00:00:00 UTC
Zero identifies the Unix epoch itself. A value such as 1700000000 is interpreted as seconds, while a thirteen-digit value is treated as milliseconds.
How the result is produced
2
UTC and local displays describe one instant
ISO and UTC forms avoid timezone ambiguity. The local form uses the timezone configured on the current device, so it can show a different clock time for the same timestamp.
Good uses
- Translate an API exp, iat, created_at, or updated_at field.
- Compare a log timestamp with a local event time.
- Create a Unix value for a deterministic test fixture.
Limits and checks
- Confirm whether the source uses seconds, milliseconds, microseconds, or nanoseconds.
- Timezone labels matter when comparing human-readable dates.
- Historical local times can be affected by timezone-rule changes.
Common questions
Why is my converted date thousands of years away?
The most common cause is a unit mismatch. A millisecond value treated as seconds is one thousand times too large, while seconds treated as milliseconds land near January 1970.
Does Unix time include a timezone?
No. It identifies an instant relative to UTC. A timezone is applied only when that instant is formatted for a person.
References and verification
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
Related Tools
JSON Formatter & Validator
Format, validate, and beautify JSON with syntax highlighting and error detection.
Base64 Encoder / Decoder
Encode text or files to Base64 and decode Base64 strings back to their original form.
SQL Formatter & Beautifier
Format and indent SQL queries for better readability across all major dialects.
HTML to Markdown Converter
Convert HTML markup into clean Markdown syntax with support for tables and lists.
Markdown to HTML Live Preview
Write Markdown and see the rendered HTML output in real time with live preview.
Diff / Patch Viewer
Visualize unified diffs and patch files with color-coded additions and deletions.