Timestamp Converter
Convert between Unix epoch timestamps and human-readable dates in both directions, runs entirely in your browser.
About this tool
Converts a Unix epoch timestamp (seconds or milliseconds since January 1, 1970 UTC) into ISO 8601, UTC, and your local time, or goes the other direction: pick a date and time and get back its epoch value. The unit (seconds vs. milliseconds) is detected automatically from the number’s magnitude, so pasting either a 10-digit or 13-digit timestamp just works.
Epoch timestamps show up constantly in logs, database columns, JWT exp/iat claims, and API responses, almost always without a label saying whether they are seconds or milliseconds, which is the single most common source of "this date is 50 years wrong" bugs. This tool removes the guesswork.
Frequently asked questions
- How does the tool know if my number is seconds or milliseconds?
- By magnitude: a seconds-based Unix timestamp for any date in the current era is 10 digits and stays that way until the year 2286, while a milliseconds-based one is already 13 digits. Anything larger than 10^12 is treated as milliseconds, anything smaller as seconds.
- Why does my local time differ from the ISO/UTC value shown?
- ISO 8601 and UTC always represent the instant in Coordinated Universal Time, while the "local time" row renders that same instant in your browser’s own timezone. Both describe the exact same moment, just displayed differently.
- What happens with negative timestamps?
- Negative epoch values represent dates before January 1, 1970 and are handled the same way as positive ones; JavaScript’s Date type supports a wide range of dates on both sides of the epoch.
- Is anything I enter sent anywhere?
- No. All conversion happens locally using the browser’s built-in Date object, no network request is made.
Continue learning
- ToolTime Zone ConverterSee one date and time across major world time zones at a glance, runs entirely in your browser.
- ToolDockerfile GeneratorGenerate a working Dockerfile for Node.js, Python, Go, or a static site, runs entirely in your browser.
- ToolDocker Compose GeneratorBuild a multi-service docker-compose.yml from a simple form, runs entirely in your browser.