Plain DatesClear date calculations, with the rules shown.

Epoch converter

Convert Unix timestamps and dates

Translate Unix seconds or milliseconds into UTC, ISO 8601, and your browser’s local time—or convert a calendar date and time back to an epoch value.

Timestamp converter

One instant, several representations

A Unix timestamp identifies an instant independently of display time zone. UTC and local formatting can show different calendar dates while referring to the same instant.

Seconds and milliseconds

0 seconds is 1970-01-01T00:00:00.000Z. A typical current timestamp has about 10 digits in seconds or 13 digits in milliseconds. Choose an explicit unit when magnitude-based detection would be ambiguous.

Limits and precision

JavaScript dates and browser locale data determine the supported range and historical zone formatting. The converter truncates displayed epoch values to whole milliseconds and does not handle leap seconds.

Days Between DatesCompare two calendar dates with a consistent end-date rule.Add or Subtract From a DateMove a date by days, weeks, months, or years.Business Days CalculatorCount or add weekdays with optional custom holidays.Date CountdownCount full calendar days to a date and download an all-day calendar event.Age CalculatorCalculate age, birth weekday, and the next birthday.Day of the WeekFind the weekday, day of year, and ISO week for a date.ISO Week NumberConvert dates to ISO weeks or look up a week’s date range.Time CalculatorAdd or subtract hours and minutes with day-offset reporting.Printable CalendarGenerate a clean monthly calendar with either week-start convention.