Developer
Encoders, converters & dev utilities
Convert Milliseconds (Epoch) to Date & Time
Convert an epoch value in milliseconds — the 13-digit timestamps produced by JavaScript Date.now() and many JSON APIs — into a human-readable date. Millisecond epoch is the number of milliseconds since 1970-01-01T00:00:00Z (UTC); dividing by 1000 gives the classic Unix seconds value. Worked example: 1700000000000 (13 digits) is detected as milliseconds and converts to 2023-11-14T22:13:20.000Z — the same instant as the 10-digit seconds value 1700000000. The tool auto-detects seconds vs milliseconds by magnitude so you never land in the wrong millennium, and shows UTC, local, and any timezone. Runs 100% in your browser. Free, no login.
Millisecond epoch = milliseconds since 1970-01-01T00:00:00Z (UTC); ÷ 1000 → the Unix seconds value
- Byte-exact worked example: 1700000000000 (13 digits, ms) → 2023-11-14T22:13:20.000Z
- Same instant as the seconds form: 1700000000 (10 digits) → 2023-11-14T22:13:20Z
- In JavaScript: new Date(1700000000000) — the Date constructor already takes milliseconds directly
- Auto-detect by magnitude (13 digits = ms) so a ms value is never misread as seconds; 100% client-side
Frequently asked questions
How do I convert milliseconds to a date?
Paste the 13-digit millisecond value and the tool interprets it as milliseconds since 1970-01-01T00:00:00Z (UTC) and renders the date. For example 1700000000000 converts to 2023-11-14T22:13:20.000Z. In JavaScript this is simply new Date(1700000000000), because the Date constructor takes milliseconds. The conversion runs in your browser and is shown in UTC, local, and your chosen timezone.
What is the difference between epoch seconds and milliseconds?
Both count from the same origin (1970-01-01T00:00:00Z, UTC); they differ only by a factor of 1000. Seconds is the traditional Unix form (10 digits today), while milliseconds is what JavaScript Date.now() and many web APIs return (13 digits). To go from milliseconds to seconds, divide by 1000; to go the other way, multiply by 1000. So 1700000000000 ms equals 1700000000 s — the same moment.
How does the tool know it is milliseconds and not seconds?
By the magnitude of the number. A present-day seconds timestamp is about 10 digits (1.7 billion), whereas the same instant in milliseconds is about 13 digits (1.7 trillion). The converter uses this heuristic to auto-detect the unit — a 13-digit value is treated as milliseconds — and lets you override it. This prevents the classic mistake of reading a millisecond value as seconds and landing in the year 55,000.