Unix Timestamp Converter

Seconds since 1970 to UTC date and back, both directions.

What it does

Unix timestamps compress any moment into one integer: seconds since the epoch at the start of 1970 UTC. Logs, databases, and APIs trade these numbers because they sort and subtract without calendars.

The tool above converts both directions in UTC. Timestamps become readable dates with ISO and millisecond forms; dates with times become epoch seconds the same way.

The default zero reads 1970-01-01 00:00:00 UTC exactly. Flipping to October 10 2026 midnight returns 1791590400 seconds (1791590400000 ms for JavaScript).

The epoch follows POSIX time definitions with MDN Date references matching the milliseconds convention. Both ignore leap seconds, counting every day as exactly 86400 seconds.

How to use

1. Pick the direction first.
2. For timestamps, enter whole seconds (negatives predate 1970).
3. For dates, pick the day with UTC time.
4. Read the conversion first for the answer.
5. Use millis form for JavaScript Date work.

Formula

epoch

1970-01-01 00:00:00 UTC, the zero point.

86400

Seconds per day, leap seconds ignored.

x1000

Milliseconds for Date constructors.

UTC throughout; local zones shift wall clocks but never the count. Range covers year 0 to 9999 inside JavaScript Date precision.

Worked example

Reference table

Limits

• UTC only; local display needs zone math.
• Leap seconds ignored by definition.
• Year 0 to 9999 inside Date precision.
• Fractional seconds round to whole millis.

Common mistakes

• Feeding millis where seconds belong (1000x off).
• Reading local midnight as UTC midnight.
• Forgetting months start at zero in code.
• Assuming leap seconds count in the number.
• Storing stamps in 32 bit past 2038.

Try it yourself

Quick checks. Answers sit tucked under each question.

Questions

Sources

• POSIX: epoch time
• MDN: Date

Related calculators