Unix Timestamp Converter
Convert seconds, milliseconds and calendar times with explicit UTC or local interpretation.
INPUT
RESULT
Enable JavaScript to convert locally.
One instant, two directions.
Choose Unix timestamp to inspect an existing value, or Date/time to convert a calendar time. Select seconds or milliseconds explicitly. Every result includes Unix seconds, Unix milliseconds, ISO 8601, UTC and your browser’s local time.
The epoch is a shared reference.
Unix time counts from 1970-01-01 at 00:00:00 UTC. Zero is the epoch; negative values are earlier. Timezones affect the calendar representation, not the underlying instant.
Your clock, on demand.
Use current time captures your device clock once. It is not a synchronized time service or a live ticker. Inputs and conversions remain in browser memory and are cleared on reset or navigation.
Make the interpretation explicit.
Are fractional seconds supported?
Yes, up to three decimal places, exactly to the millisecond. Millisecond input must be a whole number. Exponents, separators and finer precision are rejected rather than rounded. Outer whitespace is trimmed for numeric input.
Does a date mean UTC or local time?
You choose. UTC is the default. Local means the timezone configured in your browser; the resulting local display includes its offset and zone name. This tool does not offer arbitrary named-timezone selection.
What happens at a daylight-saving transition?
Nonexistent local calendar times in a clock-change gap are rejected. A repeated local time selects the earlier occurrence, following JavaScript Date semantics. Enter the corresponding UTC calendar time to choose a specific occurrence unambiguously.
What are the supported limits?
Numeric input is limited to 64 characters and the JavaScript Date range of ±8,640,000,000,000,000 milliseconds. Calendar input supports years 0001–9999 and real calendar dates. Leap seconds are not represented; seconds run from 00 through 59. Historical local offsets depend on the browser’s timezone database. Native local GMT labels use minute precision; use ISO or UTC for exact historical instants.