Clarity15 FREE TOOLS
Date & time, made clearer.
Count calendar days, compare ages, and separate weekdays from weekends.
Tools in this category
Date Addition Calculator
Add or subtract whole calendar days from a date and find the resulting weekday.
Time Duration Calculator
Find elapsed wall-clock hours and minutes between two times, including an overnight interval.
Age Calculator
Find completed years of age and total elapsed calendar days between two dates.
Date Difference Calculator
Count the days and full weeks between two calendar dates.
Business Days Calculator
Count Monday-to-Friday weekdays between two dates, excluding the end date.
Business Date Calculator
Add or subtract working days while excluding your chosen weekend and a custom holiday list.
Add Time Calculator
Add a list of hour-minute-second durations and convert the total to decimal hours.
Time Zone Converter
Convert an exact timestamp to another time zone, including the daylight-saving offset for that instant.
Meeting Time Zone Planner
Compare one proposed meeting instant across several time zones and identify date changes.
Recurring Date Generator
Generate dates at a fixed day interval for schedules, reminders and repeating plans.
Monthly Calendar Generator
Build a plain-text month calendar with Monday-first or Sunday-first weeks, ready to copy.
Day of Year Calculator
Find a calendar date’s ordinal day number and the days remaining in its year.
Leap Year Calculator
Check whether a Gregorian calendar year contains February 29 and 366 days.
ISO Week Number Calculator
Find the ISO week number, week-year and Monday-through-Sunday range for a date.
Work Hours Calculator
Calculate net shift hours after an unpaid break, including shifts that end the next day.
Choosing a tool for date & time
Our date tools use calendar dates rather than local clock times, so daylight saving changes do not add or subtract a day. Date ranges include the start and exclude the end unless stated otherwise.