How to use the epoch milliseconds and seconds converter
Paste a timestamp and the page decides whether it is seconds or milliseconds from the digit count, then prints the rule it used alongside the result. You can also pick the unit yourself, including microseconds and nanoseconds. The table shows the UTC time you would get reading the same number under all four units, side by side, so the right reading is easy to spot. Change the display zone and you get both that local time and UTC.
How the conversion works
The input is normalized to whole nanoseconds and handled with BigInt, because a 19-digit nanosecond value sits past the safe integer range in JavaScript. Date output follows ISO 8601 and the IANA time zone data built into your browser, verified in October 2026. The copy box holds plain text with no separators so the values paste straight into code.
Limits worth knowing
The digit rule is a convention, so values near 12 digits are genuinely ambiguous. That is why the page lists every reading instead of insisting on one. On daylight saving transition days a local time can appear twice or not at all, so record the reference zone whenever you feed these values into scheduling logic. Digits below a millisecond are dropped from the date display but kept in the second and millisecond figures.
Frequently Asked Questions
Auto detection reads an integer part of 12 digits or more as milliseconds and anything shorter as seconds. The page prints the rule it applied and also lists the time you get under all four units, so you can compare for yourself.
Systems that store epoch seconds in a signed 32-bit integer stop at 2,147,483,647 seconds, which is 2038-01-19T03:14:07Z. The page raises a warning once your value passes that point.
It does not show a live clock or let you pick a date to turn into an epoch value. It stays on unit detection, conversion and time zone display. Daylight saving gaps and repeats follow the time zone data in your browser.