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Dates & time

Unix Timestamp Converter

Convert Unix timestamps to UTC ISO dates or convert a UTC date and time to a timestamp. Choose seconds or milliseconds explicitly instead of guessing from the number’s length.

  • Explicit formulas and worked examples
  • Check your inputs, then calculate
  • Data is calculated in this browser only

Check the stated input format, calculation convention and limits before using the result.

Your inputs

Local calculation

Check the example inputs, then calculate. Your values stay in this browser.

Negative timestamps represent times before the Unix epoch.

Calculation notes

Understand the Unix Timestamp Converter

Unix Timestamp Converter validates direction, unix timestamp, timestamp unit, utc date, utc time before applying the displayed equation. Negative timestamps represent times before the Unix epoch.

Formula and logic

What is the formula for the Unix Timestamp Converter?

Unix Timestamp Converter: timestamp seconds = UTC milliseconds since 1970-01-01T00:00:00Z / 1000. Input definitions: mode = Direction; timestamp = Unix timestamp; unit = Timestamp unit; date = UTC date; time = UTC time. Use the selected convention throughout the calculation.

Worked example

How can I reproduce the Unix Timestamp Converter example?

Unix Timestamp Converter baseline input: Direction: Timestamp to UTC date; Unix timestamp: 0; Timestamp unit: Seconds; UTC date: 1970-01-01; UTC time: 00:00. Output: UTC date and time = 1970-01-01T00:00:00.000Z. Substitute these values into the displayed equation to reproduce the result.

How to read the result

How should I interpret the Unix Timestamp Converter result?

  • Read utc date and time with its stated unit and convention. The default example and the independent worked scenario use different inputs, so compare the assumptions before comparing the numbers.
  • Change one input at a time and use the equation to explain the result; do not mix unit, grade-scale, time-zone or rounding conventions across comparisons.
Limits and assumptions

What limits apply to the Unix Timestamp Converter?

  • Negative timestamps represent times before the Unix epoch.
  • No leap-second representation or local-time-zone conversion is included.
  • Calendar-date inputs and calculated calendar dates must stay within years 0001–9999.

Content and calculation reviewed:

Understand the calculation

How to use it and the math behind it

Read the complete explanation

Four steps to check your inputs and results

  1. Convert Unix timestamps to UTC ISO dates or convert a UTC date and time to a timestamp. Choose seconds or milliseconds explicitly instead of guessing from the number’s length.
  2. Enter Direction, Unix timestamp, Timestamp unit, UTC date, UTC time in the stated format. Baseline values are for reproduction.
  3. Check the output unit and convention: Read utc date and time with its stated unit and convention. The default example and the independent worked scenario use different inputs, so compare the assumptions before comparing the numbers.
  4. Change one input and compare the result. Negative timestamps represent times before the Unix epoch. No leap-second representation or local-time-zone conversion is included. Calendar-date inputs and calculated calendar dates must stay within years 0001–9999.

Unix Timestamp Converter: calendar conventions

A Unix timestamp measures seconds or milliseconds from the UTC epoch. A value of 1000 in millisecond mode is 1970-01-01T00:00:01.000Z, while 1000 in second mode is 16 minutes 40 seconds after the epoch. The suffix Z denotes UTC. Negative values precede the epoch; local clock formatting is a separate operation.

timestamp seconds = UTC milliseconds since 1970-01-01T00:00:00Z / 1000

The detailed guide adds variable definitions, a reproducible example, a practice question and model limitations.

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