Unix Timestamp Converter.
The same instant. Made clear.

Choose seconds, milliseconds, microseconds or nanoseconds explicitly. Seconds accept up to 9 decimal places, milliseconds up to 6, microseconds up to 3; nanoseconds must be integers. Values are processed exactly with integer arithmetic, including negative fractions before 1970. Scientific notation, comma separators, unit suffixes and excess decimal places are rejected. Units are never guessed from the number of digits.

Use YYYY-MM-DD for UTC midnight, or YYYY-MM-DDTHH:mm:ss with optional 1–9 fractional digits and a required Z or ±HH:mm offset. Calendar dates and offsets are validated, including leap years. Impossible dates, missing time offsets, 24:00, leap seconds and the unknown offset -00:00 are rejected. Use Z or +00:00 for known UTC. Supported UTC result years are 0001–9999.

The conversion engine keeps exact integer nanoseconds and returns epoch values as decimal strings. UTC ISO output always includes 9 fractional digits. A long epoch number is not converted to a JavaScript floating-point number. Millisecond-based display APIs are used only for calendar/time-zone presentation; the original fractional digits are retained. Extra decimal places are rejected instead of rounded.

A local wall time can occur twice or not occur at all when daylight-saving rules change. This tool requires an explicit numeric offset for date-time input. The time-zone selector changes only the inspector’s display of an already known instant. It does not reinterpret input. Selected-zone presentation uses the browser’s time-zone database, which can vary with browser updates and historical rules.

The button replaces the input with one snapshot of the device clock in the selected input format, then converts it. It does not run a timer or silently update results. Device clock accuracy and precision depend on the browser and system; adding zeros for microseconds or nanoseconds does not create finer clock precision.

Convert up to 1,000 nonempty lines, with at most 256 KiB of UTF-8 input. Blank lines are skipped, surrounding input whitespace is trimmed and source line numbers are retained. Each trimmed timestamp or date may contain up to 128 characters. Import reads UTF-8 text and omits a leading UTF-8 BOM. Results show 50 rows per page; complete exports include every result. Processing runs in a local worker with 5-second startup and 10-second execution deadlines, and Cancel discards partial results.

Copy results or download TXT for valid conversions in the selected output format. Copy an individual result from its row, or copy the inspected row as JSON with its complete original input and exact values. JSON and CSV retain every row, including invalid-input diagnostics; JSON also keeps source input, while CSV omits that untrusted column. All ISO exports remain UTC; the inspector’s display zone is not exported. Import long epoch columns as text in spreadsheet software to prevent automatic numeric rounding. Changing output format refreshes exports without reprocessing input.

Conversions happen locally in your browser. This tool does not upload input or save history. Clear removes input, results and temporary download links. Normal site analytics and feedback services may still load. Unix time here follows the usual non-leap-second timeline; this is not a leap-second-aware scientific time scale.