Time and Date Calculators

Count calendar days between two dates.

Add or subtract days, weeks, months, and years.

Measure elapsed time between two date-times.

Find the weekday and day-of-year for a date.

Calculate ISO week numbers for any date.

Calculate age and special age milestones.

Find palindrome dates and same-calendar years.

Run date calculations for multiple rows.

Generate repeating dates from a start date.

Find the 1-indexed day-of-year (DOY) for a date.

ISO 8601 and US Sunday-start week numbers side by side.

Convert a calendar date to ISO 8601 YYYY-DDD form.

Find Q1–Q4 plus quarter start and end dates.

Count weekdays between two dates.

Find a date after a number of working days.

Calculate invoice due dates from payment terms.

Calculate support deadlines in business hours.

Find FY for any date — US federal, UK, custom starts.

Estimate due date from LMP using Naegele's rule (LMP + 280d).

Total worked hours per day and per week with breaks.

Add business days, skipping public holidays in 200+ countries.

View a full year calendar.

Browse public holidays by country and year.

See moon phases for a month.

Find seasons, moon, meteor, and eclipse pages.

Sunrise and sunset times for any date and location.

Western Christian Easter Sunday for any Gregorian year.

Convert one date-time between IANA timezones.

Compare offsets between two timezones.

Find overlapping hours across timezones.

Share one event time across many cities.

Show current browser-local time.

Show current UTC time and related tools.

Browse countdown and event date pages.

Create a shareable countdown URL and embed.

Track elapsed time since a date.

Embed current year progress in an iframe.

Convert Unix timestamps and ISO dates.

Convert timestamp lists with row-level errors.

Convert numbers and Roman numerals.

Check the Gregorian leap-year rule.

Convert UTC date/time to astronomical Julian Day (JD).

Parse a 5-field cron expression — see the next 5 firings.