2026topopentools

Unix Timestamp Converter

Convert Unix epoch timestamps to readable dates and dates back to timestamps — in seconds or milliseconds, both directions.

Understanding the Unix Timestamp Converter

This converter translates between Unix timestamps (epoch time) and human-readable dates in both directions. Unix time counts the seconds elapsed since 00:00:00 UTC on 1 January 1970, the universal reference point used in logs, APIs, databases, and programming languages. Paste an epoch number to see the matching calendar date and time, or pick a date to get its timestamp. It is aimed at developers, sysadmins, and analysts who debug logs, compare records, or build time-based features and need a quick, accurate conversion in local time and UTC.

How it works

Enter a value in seconds or milliseconds; the tool detects the magnitude (10-digit values are seconds, 13-digit are milliseconds) and builds a JavaScript Date from it. It then formats that instant in both UTC and your browser's local time zone, including the day of week and ISO 8601 string. Converting the other way, it parses the date you choose and returns Math.floor(Date.getTime()/1000). All math happens in your browser, so nothing is uploaded. Remember the displayed local time depends on your machine's zone and daylight-saving rules, while UTC stays fixed.

date = epoch_seconds / 86400 days since 1970-01-01 UTC; epoch_seconds = floor(Date.getTime() / 1000)

Worked example

The timestamp 1700000000 converts to Tuesday, 14 November 2023, 22:13:20 UTC. There are 86,400 seconds in a day, so dividing by that and adding to the 1970 epoch lands on that date. Going the other way, midnight UTC on 1 January 2025 (2025-01-01T00:00:00Z) is the timestamp 1735689600. Multiply by 1000 to get the millisecond form, 1735689600000, which is what JavaScript's Date.now() returns.

Tips & common mistakes

  • Confirm whether your value is in seconds or milliseconds; a 1000x error turns 2024 into the year 56,000 or pushes a date back to 1970.
  • Timestamps are absolute UTC instants. Time zones and daylight saving only affect display, not the stored number.
  • 32-bit signed epoch seconds overflow on 19 January 2038; use 64-bit storage to avoid the Year 2038 problem.
  • Negative timestamps are valid and represent dates before 1970.
  • Leap seconds are not counted in Unix time, so it can differ from true astronomical UTC by a few seconds.

Related tools

JSON Formatter & ValidatorFormat, beautify, minify, and validate JSON with clear error messages.Base64 Encode / DecodeEncode text to Base64 or decode Base64 back to text, with full Unicode support.URL Encode / DecodePercent-encode or decode text for safe use in URLs and query strings.Hash GeneratorGenerate MD5, SHA-1, SHA-256, and SHA-512 hashes from any text.

Frequently Asked Questions

What is a Unix timestamp?

A Unix timestamp (or epoch time) is the number of seconds that have elapsed since January 1, 1970 UTC. It is a simple, timezone-independent way to represent a moment in time.

Seconds or milliseconds?

Unix timestamps are traditionally in seconds (10 digits today), but JavaScript and many APIs use milliseconds (13 digits). This tool handles both — just pick the unit.

Which timezone is shown?

The result shows the date in UTC, in your local timezone, and in ISO 8601 format so you can use whichever you need.