Unix Timestamp Converter

Convert between Unix epoch time (seconds or milliseconds), ISO 8601 strings, and human-readable local / UTC representations. Live updates as you type. Handles ms-precision and the year 2038 boundary correctly.

About Unix timestamps

A Unix timestamp is the number of seconds since 1970-01-01 00:00:00 UTC, ignoring leap seconds. Standard since the early days of Unix, used everywhere from filesystem mtimes to OAuth token expiry to database timestamps.

The "millisecond timestamp" variant (13 digits for current times) is what JavaScript's Date.now() and Java's System.currentTimeMillis() return. The tool auto-detects: 10-digit values are seconds, 13-digit are milliseconds.

The year 2038 problem

A 32-bit signed integer overflows at 2147483647 = 2038-01-19 03:14:07 UTC. Any legacy system still using 32-bit time_t will wrap to a negative number then. Modern systems use 64-bit time_t, which doesn't overflow until year 292 billion. If you're working with embedded systems or legacy databases, check your timestamp column width — INT vs BIGINT is the deciding factor.