Time & Date Tools
Calendar maths is full of traps — months of different lengths, leap years, week numbering. These tools handle them correctly and explain what they counted.
How dates are counted here
All date tools use the proleptic Gregorian calendar and work with whole calendar days, so results are not affected by time zones or daylight-saving changes. When a question is ambiguous — such as whether to count both the start and end date — the tool gives you the choice and says what it counted. The guide how date calculations work explains leap years, month lengths and ISO week numbers.
Date calculations
- Days Between DatesCount the days between two dates, optionally including the end date.
- Date DifferenceThe gap between two dates in years, months and days, and in total units.
- Age CalculatorExact age in years, months and days, plus total days and next birthday.
- Add/Subtract DatesAdd or subtract years, months, weeks and days from a date.
- Business DaysCount working days between dates, or add working days to a date.
- Day of the WeekFind the weekday for any date, plus its day of the year and ISO week.
- Week NumberISO 8601 week number for a date, or the dates of a given week.
- Leap Year CheckerCheck whether a year is a leap year and find the nearest leap years.
Time calculations
- Time CalculatorAdd or subtract durations, find the time between two clock times, or add time to a clock.
- Hours Worked CalculatorAdd up a week of shifts with breaks, overnight shifts and decimal hours.
- 12h ↔ 24h TimeConvert AM/PM times to the 24-hour clock and back.
- Time Unit ConverterConvert between milliseconds, seconds, minutes, hours, days and weeks.
Timers
Run in your browser tab; nothing is installed.
Time unit conversions
- Hours to MinutesConvert hours to minutes with the formula and a quick table.
- Minutes to HoursConvert minutes to hours with the formula and a quick table.
- Seconds to MinutesConvert seconds to minutes with the formula and a quick table.
- Minutes to SecondsConvert minutes to seconds with the formula and a quick table.
- Hours to SecondsConvert hours to seconds with the formula and a quick table.
- Seconds to HoursConvert seconds to hours with the formula and a quick table.
- Days to HoursConvert days to hours with the formula and a quick table.
- Hours to DaysConvert hours to days with the formula and a quick table.