Unix Timestamp Converter

The hard part of epoch conversion is not the arithmetic, it is knowing which unit you are holding. 1700000000 is November 2023 in seconds and January 1970 in milliseconds, and a wrong guess sends a support ticket chasing an event that never happened. The Timestamp Converter guesses from magnitude and lets you override it.

A live clock at the top counts the current epoch second by second beside your local time, with a Use Now button that drops the current value into the input. Below it the conversion runs in both directions: an epoch number expands into 9 formats, and a date picker collapses back into 4.

Every rendered value uses your machine's own locale and time zone, so Local String and Day of Week differ between two people reading the same page. ISO 8601 and UTC String are the two that do not move, which makes them the right ones to paste into a bug report. It all computes locally.

Getting From an Epoch Number to a Local Time

1. Paste the number into the field under Unix Timestamp → Human Date, or press Use Now to load the current second.
2. Leave the unit selector on AUTO unless the result looks wrong, then force S or MS. The tooltip on each spells out what it does.
3. Read across the 9 cards. ISO 8601 and UTC String are absolute, Local String and the two split date and time cards follow your machine, and Day of Week answers the question people usually meant to ask.
4. Hover a card and take its copy button. Each card copies its own value on its own, so you never have to trim a longer string down.
5. Use the Human Date → Unix Timestamp picker for the reverse. It hands back seconds, milliseconds, ISO and UTC together, and the picker is interpreted in your local zone rather than UTC.

Tricky Inputs: Seconds Versus Milliseconds

• Auto-detection compares against 100 billion. Below that the number is treated as seconds, above it as milliseconds. In seconds, 100 billion is somewhere around the year 5138, so no realistic date is misread.
• Counting digits instead would be worse, and used to be. A millisecond value such as 946684800000 for January 2000 has only 12 digits, so a 13-digit rule classified it as seconds and multiplied it again, landing near the year 31,970.
• Negative values are legal and mean dates before 1970. Auto mode compares the absolute magnitude, so a negative second count is still read as seconds.
• Anything unparseable reports Invalid timestamp. beneath the field, and a date the engine cannot represent does the same rather than displaying a row of NaN.
• The date picker offers minute resolution, so the seconds component of anything you enter there is 0. Use the epoch field directly when the exact second matters.
• The live clock ticks once a second from your device, so it inherits any drift in the system clock. Do not use it to argue with a server about a token expiry.