Date Converters

Simplify your time calculations. Convert a local date/time into UNIX timestamp, ISO 8601, day of week and day of year — all in one place.

Date

Works in your browser’s local timezone. Year must be ≤ 9999.

Output

To Timestamp (ms since 1970-01-01 UTC)
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To ISO 8601
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To Day of Week
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To Day of Year
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ISO 8601 uses UTC (“Z”). The day of week and day of year are computed in your local timezone.

About Date

The "Date" class is a data structure that allows representing and manipulating dates in computer systems. It enables storing information about the year, month, day, hour, minute, second, and millisecond of a given date.

Evolution and Standards

Over time, several standards and conventions have emerged for date representation. These include the ISO 8601 format, the UNIX timestamp format, and the date format commonly used in database systems. The "Date" class has been adapted to support these standards and facilitate interoperability between systems.

Date conversions

Date to Timestamp

Converting date to a timestamp (or milliseconds) allows you to represent a specific moment in time as a numeric value. Timestamps are commonly used in databases and computer systems for accurate timekeeping and data manipulation. If you are looking for the opposite conversion, you can visit: milliseconds to date.

Date to ISO 8601

Converting date to ISO 8601 format ensures standardization and compatibility across different systems and applications. ISO 8601 is widely adopted for representing dates and times in a clear and unambiguous way, facilitating data exchange and communication.

Date to Day of Week

Converting date to the day of the week provides valuable information about the temporal context of a given date. Knowing the day of the week is useful for scheduling events, planning activities, and analyzing trends over time.

Date to Day of Year

Converting date to the day of the year allows you to express a date's position within a calendar year as a numeric value. This information is valuable for various purposes, such as calculating elapsed time, tracking seasonal patterns, and organizing data chronologically.

Tips & Best Practices

  • Timezones matter: your input is interpreted in the browser’s local timezone, while ISO 8601 is emitted in UTC (Z).
  • Leap years: day-of-year ranges from 1–365 (or 366 in leap years). This tool handles both cases automatically.
  • Validation: for compatibility with most libraries, years are limited to ≤ 9999.
  • Copy quickly: use the Copy buttons to move results into your code, logs or spreadsheets.

Common Use Cases

  • Generating timestamps for database rows, cache keys, or API payloads.
  • Normalizing user input into ISO 8601 for backend services.
  • Building reports by grouping entries by day of week or day of year.

How to use this date converter

  1. Select date and time: Use the datetime picker to choose your desired date and time
  2. Press Enter or Convert: Hit the Convert button or press Enter for instant results
  3. Copy results: Click any Copy button to copy the converted value to your clipboard
  4. Use Now button: Get current date and time instantly

Understanding the output formats

  • Timestamp (ms): Milliseconds since January 1, 1970 UTC (UNIX epoch)
  • ISO 8601: International standard date format (YYYY-MM-DDTHH:mm:ss.sssZ)
  • Day of Week: Human-readable day name in your local timezone
  • Day of Year: Numeric position of the date within the year (1-366)

Related tools

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