Date & time
Add days, weeks, leap years, and countdowns on this device.
Unix Timestamp Converter
Unix seconds/millis ↔ date, with timezone display.
Shelf Life
Check expiry from produce date + days, or an expiry date.
Baby Milestones
Baby milestones with full-month/100-day/year dates.
Seven Sevens Memorial
七七 memorial dates with first and last.
Countdown (Days)
Days (and weeks/hours) until a target date.
Date Difference
Count days, weeks, and calendar span between dates.
Time Zone Converter
Show a time in two common IANA zones.
Business Days
Count weekdays between dates, with weekend options.
Add Days
Add calendar days; shows result weekday.
Add Business Days
Add weekdays only; shows result weekday.
ISO Week Number
ISO-8601 week and ISO year.
Leap Year Check
Is leap year? Plus next/previous leap years.
Days Until Date
Days from a start date (default today) to a target.
Calendar Quarter
Q1–Q4 plus quarter start, end, and day count.
Day of Year
Ordinal day 1–366 plus remaining days in the year.
Add Months
Add months; shows result weekday.
Weekday Name
Weekday name, ISO 1–7, and Sunday-based 0–6.
Days in Month
Days in a month; leap flag for February.
Is Weekend
Weekend flag plus weekday number and name.
Add Years
Add years; shows result weekday.
End of Month
Last day of the month plus weekday and day count.
Start of ISO Week
Monday and Sunday of that ISO week.
Workdays in Month
Monday–Friday count in a month.
Quarter Range
First and last day of that quarter.
Next Weekday
Next ISO weekday; optional include today.
Julian Day Number
Gregorian date to JDN and Modified Julian Day.
Start of Month
First day of the month plus weekday.
Add Weeks
Add weeks; shows result weekday.
Month Difference
Month and day span; optional absolute.
Year Difference
Completed years and day span; optional absolute.
Previous Weekday
Previous ISO weekday; optional include today.
Week of Month
Week-of-month plus how many weeks the month has.
Start of Year
January 1 with weekday and year.
End of Year
December 31 with weekday and year.
Start of Quarter
First day of that calendar quarter.
End of Quarter
Last day of that calendar quarter.
Days in Year
365 or 366 for a year.
Is Same Day
Same-day check with both dates.
Age on Date
Completed years from birth to a date.
Business Days Until
Business days with calendar span.
Minutes Between
Minutes between two datetimes.
ISO Ordinal Date
YYYY-DDD ordinal date.
Hours Between
Hours between with min/sec.
Seconds Between
Seconds between with min/hour.
Is Same Month
Same month with dates.
Is Same Year
Same year with dates.
First Weekday of Month
First Mon–Sun date in a month.
Last Weekday of Month
Last Mon–Sun date in a month.
Weekdays Between
Weekdays with calendar span.
Add Quarters
Add quarters with weekday.
Date from Ordinal
Ordinal date with leap flag.
Unix from YMD
Unix from date with weekday and ms.
YMD from Unix
Date from Unix with weekday and ISO.
Is Past Date
Past flag plus days from today.
Is Future Date
Future flag plus days from today.
Add Hours
Add hours with ms.
Add Minutes
Add minutes with ms.
Middle of Month
Mid-month date with day and weekday.
Nth Weekday of Month
Nth Mon–Sun date in a month.
Weekday Name
English weekday name for a date.
Hours Until
Hours until an instant; also days and minutes.
Inclusive Day Span
Inclusive day span with nights.
Is Same ISO Week
Same ISO week with week/year.
Date from Julian
Julian day to date with weekday and year.
Month Name
English month name for a date.
Seconds Until
Seconds until an instant; also hours and days.
End of ISO Week
ISO week end with week start and weekday.
Add Business Weeks
Add business weeks with weekday.
Is Leap Day
Leap-day flag plus leap-year flag.
Quarter of Unix
Calendar quarter from Unix seconds.
YMD Compare
Compare dates with day delta.
Days in Quarter
Days in quarter with start and end.
Days Elapsed in Year
Day-of-year with percent through the year.
Days Remaining in Year
Days left in the year with percent remaining.
Simple Week Number
Simple week number with year and day-of-year.
Time of Day Bucket
Morning/afternoon/evening/night.
Parse YMD Parts
Split a date into Y/M/D.
Format YMD Slash
Y/M/D slash date with ISO and weekday.
Months Until
Months and days from today; optional absolute.
Years Until
Years and days from today; optional absolute.
Next Month Same Day
Next month same day with weekday and year.
Prev Month Same Day
Previous month same day with weekday and year.
Is Month End
Month-end flag with day and last day.
Is Month Start
Month-start flag with day and last day.
Hour of Day
Hour with minute and second from ISO time.
Minute of Hour
Minute with hour and second from ISO time.
Add Years and Months
Shift by years and months together.
Fortnights Between
14-day spans between two dates.
Days Since Epoch
Days since 1970-01-01 with years and weekday.
ISO Week Year
ISO week number and year.
Next Quarter Start
Next quarter start with weekday and quarter.
Prev Quarter End
Previous quarter end with weekday and quarter.
Same Weekday Next Week
Same weekday next week with day and year.
Business Days in Range
Business days with calendar span.
Flip Clock
Local hours, minutes, and seconds.
September 28 Countdown
Days until the next September 28.
Death Anniversary
First- and third-year Gregorian dates.
BaZi Four Pillars
Four pillars from birth date and hour.
Lunar ↔ Solar
Convert Gregorian and Chinese lunar dates.
Chinese Zodiac
Animal sign from a year.
Zodiac Sign
Western sun sign from a birth date.
World Clock
Show one instant across time zones.
Meeting Planner
Map an hour in zone A to zone B.
Holiday Countdown
Days until a holiday date.
Exam Countdown
Days until an exam date.
Wedding Countdown
Days until a wedding date.
Ovulation Window
Estimate fertile window from LMP.
Period Cycle
Project next period dates.
Pomodoro Planner
Build a work/break schedule.