25 FREE TOOLS · ◴
Date & time calculators
Calculate ages, calendar intervals, business days and clock durations.
Calendar dates & age
Work with Gregorian dates, birthdays, month lengths and date intervals.
Explore topic ↗4 calculatorsBusiness days & weekends
Count weekdays and apply a holiday list that you supply.
Explore topic ↗3 calculatorsTime durations & decimal hours
Combine durations and translate between decimal hours and hours-minutes notation.
Explore topic ↗1 calculatorsTime-zone conversion
Convert a local date-time between supported named time zones.
Explore topic ↗All date & time calculators
Age Calculator
Find completed years of age between a birth date and an as-of date.
Date Difference Calculator
Count calendar days from a start date to an end date.
Add Days to Date Calculator
Find the calendar date a chosen whole number of days after or before another date.
Business Days Calculator
Count Monday-to-Friday dates in a start-inclusive, end-exclusive interval.
Add Business Days Calculator
Move a date by a signed number of Monday-to-Friday working days.
Day of the Week Calculator
Find the weekday name for a Gregorian calendar date.
ISO Week Number Calculator
Find ISO week-year and week number for a chosen date.
Days in Month Calculator
Find the number of days in a Gregorian month, including leap-year February.
Day of Year Calculator
Find the ordinal position of a date within its Gregorian year.
Age in Days Calculator
Count complete calendar days between a birth date and an as-of date.
Weeks Between Dates Calculator
Express a signed calendar-day interval as decimal weeks.
Year Progress Calculator
Find the percentage of calendar dates elapsed at the start of a chosen date.
Anniversary Year Calculator
Find the anniversary calendar year from an original year and a selected anniversary number.
Leap Year Calculator
Check whether a Gregorian calendar year has 366 days.
Hours Minutes to Decimal Calculator
Convert a duration in whole hours and minutes into decimal hours.
Decimal Hours to Hours Minutes Calculator
Express a non-negative decimal-hour duration as whole hours and rounded minutes.
Unix Timestamp to UTC Calculator
Convert Unix seconds to a UTC date-time string.
Date to Unix Timestamp Calculator
Convert a civil date at UTC midnight into Unix seconds.
Time Zone Converter
Convert a local date and time between named time zones using the browser’s time-zone rules.
Time Calculator
Add or subtract signed durations written as hours, minutes and optional seconds.
Add Months to Date Calculator
Move a civil date by whole calendar months with an explicit end-of-month rule.
Add Years to Date Calculator
Move a Gregorian date by whole years with leap-day clamping.
Weekend Days Between Dates Calculator
Count Saturdays and Sundays in a start-inclusive, end-exclusive calendar interval.
Business Days Excluding Holidays Calculator
Count weekdays while excluding a holiday-date list supplied by you.
Calendar Months Between Dates Calculator
Find the signed difference between two Gregorian month labels.
Make your inputs count
These tools use Gregorian calendar dates with explicitly stated interval boundaries. Weekday tools do not infer public holidays. Durations, civil dates and time-zone-aware instants are different quantities; choose the corresponding tool.