Timestamp Converter

A Unix timestamp is the count of seconds since 00:00:00 UTC on January 1, 1970, the moment called the Unix epoch. The POSIX standard treats every day as exactly 86,400 seconds and ignores leap seconds, so the value is a plain running count. Databases, APIs, and log files store time this way because the number is timezone-free and sorts in chronological order. This tool also reads and shows millisecond timestamps, which use the same epoch.

It checks the absolute value: anything 10^11 or larger counts as milliseconds, anything smaller counts as seconds. As milliseconds, 10^11 lands on March 3, 1973; as seconds, it lands in the year 5138, so real-world values on either side never overlap. If a number sits near the boundary, pick the unit yourself in the dropdown to override the guess.

Yes. Enter a negative timestamp and you get a date before the epoch, and the date-to-timestamp direction returns negative numbers too. JavaScript holds time as a 64-bit floating-point count of milliseconds, so the 32-bit overflow behind the year-2038 bug never applies here. The supported window runs roughly 273,000 years on each side of 1970.

When you enter a value like 2026-01-15T10:30:00 with no zone marker, the tool appends a Z and reads it as UTC. Without that rule, the same text would shift by your computer's offset, a frequent cause of off-by-one-day bugs. To use a specific zone, add an explicit offset such as +02:00, or switch the timezone setting to local.

It matters wherever a system stores Unix seconds in a signed 32-bit value, which overflows after 03:14:07 UTC on January 19, 2038. Safety depends on the language runtime, operating system, database type, driver, and schema. Do not assume every JavaScript, Python, PostgreSQL, MySQL, C, or embedded path uses the same representation.