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Unix Timestamp Converter

Convert Unix time ↔ human dates. Seconds and milliseconds auto-detected.

Current timestamp

Timestamp → Date

Date → Timestamp

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Turn the number in a log line into a real date and time, and back

Server logs, databases and token expiry fields often store time as a number like 1724822400. This tool turns that number into your local time and a UTC date, and turns a date you pick into a timestamp in seconds and milliseconds. It tells seconds from milliseconds by the number of digits.

A closer look

A Unix timestamp counts the seconds since midnight UTC on January 1, 1970. The same moment has the same number everywhere on Earth, which is why servers use it to exchange times and why it is easy to subtract one event from another. The catch is that some systems count in seconds (Linux, the exp field in a JWT) and others in milliseconds (JavaScript’s Date.now(), Java), so it is easy to misread the digits. The so-called year 2038 problem lives here too: at 2147483647 seconds, 03:14:07 UTC on January 19, 2038, a signed 32-bit counter runs out.

The converter accepts digits only. Up to 12 digits are read as seconds and 13 or more as milliseconds, and the result ends with “(read as seconds)” or “(read as milliseconds)” so you can see which rule applied. Each result shows your device’s local time in US month/day/year order, marked “local”, followed by the ISO 8601 UTC form ending in Z. The reverse direction uses a date-and-time picker that goes down to seconds; the time you pick is interpreted in your device’s time zone, and both the seconds and milliseconds values are shown.

How to use it

The Current timestamp box at the top updates every second. The Copy button next to it copies only the 10-digit seconds value, not the date in parentheses.
Paste a number into Timestamp → Date and press Convert to see the local date and the UTC form.
Under Date → Timestamp, pick a date and time and press Convert; the result lists the value in “(seconds)” and in “(milliseconds)”.
To double-check, paste the seconds value back into the top converter. If it shows the time you picked, the conversion is right.

When it helps

Matching an incident to a logConvert the epoch value in a log line to local time and line it up with the moment a user reported the error.

Checking a token’s lifetimePaste the exp and iat values from a decoded JWT to see when the token was issued and when it expires. Both are in seconds.

Scheduling through an APIPick “the 1st of next month, 9:00 AM” in the date box to get the seconds value a scheduler or API expects.

Probing the 2038 limitEnter 2147483647 to see the last moment a signed 32-bit time can hold, useful when judging whether an old system’s far-future expiry dates are safe.

Common snags

It says “Digits only, please.”Decimals, minus signs and spaces inside the number are rejected. For a value like 1724822400.123 from Python’s time.time(), enter only the part before the dot. Negative timestamps, meaning dates before 1970, cannot be converted here.

The year comes out in the tens of thousands, or it says “That value cannot be converted.”You have a 16-digit microsecond or a 19-digit nanosecond value. Everything with 13 or more digits is read as milliseconds, so drop the last 3 digits of a 16-digit value or the last 6 of a 19-digit value before converting.

Date → Timestamp is off by several hours.The picker is read in your device’s time zone, and so is the local time in the results. If you need the timestamp for a UTC time, convert the result back, read the ISO line, which is always UTC, and adjust by your offset.

A spreadsheet date such as 45531 comes out in early January 1970.Spreadsheets store dates as days counted from 1900, not as Unix seconds, so the tool reads that five-digit number as a few hours after the 1970 epoch. Convert it first with (serial − 25569) × 86400, which gives the Unix seconds for that date at midnight UTC.

Tip When you need milliseconds, take the “(milliseconds)” value from Date → Timestamp instead of adding zeros to the copied current timestamp by hand; it avoids digit-count slips.

Notes

How are seconds and milliseconds told apart?

10-digit numbers are read as seconds, 13 digits or more as milliseconds — automatically.