Calculator hub

Date & Time calculators and tools

Date, age, duration, deadline, and business-day calculators.

Age CalculatorCalculate age in years, months, and days from a date of birth.Day of Week CalculatorFind which weekday a date falls on, with a selected-date check and simple calendar notes.Leap Year CalculatorCheck whether a year is a leap year, how many days it has, and the next leap year.Calendar CalculatorCheck a month calendar summary with days in month, first weekday, last date, and calendar row count.Add Days CalculatorAdd or subtract a number of calendar days from a start date and see the target date and weekday.Anniversary CalculatorFind the next anniversary date, days remaining, anniversary number, and completed anniversary years.Birthday CalculatorCalculate current age, next birthday date, days until birthday, and the age being reached.Chronological Age CalculatorCalculate chronological age between a birth date and an as-of date in full years, months, and remaining days.Day CounterCount elapsed or inclusive days between two dates, with weeks and direction context.Month CounterCount completed calendar months and remaining days between two dates, plus an approximate month total.Date Difference CalculatorCalculate the number of days, weeks, months, and years between two dates.Days From Today CalculatorFind the date a selected number of days from today.Time Duration CalculatorCalculate the duration between two times in hours and minutes.Unix Timestamp ConverterConvert Unix timestamps in seconds or milliseconds into UTC ISO date-time values and readable time parts.Decimal Time ConverterConvert decimal hours into hours, minutes, seconds, total minutes, and total seconds.Minutes to Hours ConverterConvert minutes into decimal hours, hours-and-minutes format, and seconds for timesheets or schedules.Time Zone ConverterConvert a selected time between named timezones with daylight saving time rules.Business Days CalculatorCount weekdays across a selected date range.Countdown to a Date CalculatorCount the number of days remaining until a selected date.Week Number CalculatorFind the week number for a selected date.UTC to Local Time ConverterConvert a UTC date and time into a selected local timezone.

Tool paths

Choose the right date & time path

Start with the calculator closest to the question, then move sideways to related tools without returning to search.

Calendar checks

Answer weekday, date difference, leap year, and week-number questions from the same hub.

Calendar calculatorMonth summary, days, first weekday, and calendar rows.Day of week calculatorFind the weekday for any selected date.Leap year calculatorCheck whether a year has 366 days.Date difference calculatorElapsed days between two dates.Business days calculatorWeekdays between two dates.Week number calculatorISO week number for a date.

Personal dates and counters

Count birthdays, anniversaries, days, and months without leaving the date-and-time cluster.

Add days calculatorAdd or subtract calendar days from a start date.Day counterElapsed or inclusive days between two dates.Month counterCompleted calendar months and remaining days.Birthday calculatorCurrent age, next birthday, and days until birthday.Anniversary calculatorNext anniversary date, number, and days remaining.Chronological age calculatorExact age in years, months, and days.Days from today calculatorAdd days to today or another start date.

Useful starting points

Start with these date & time tools

Day of week calculatorFind which weekday a date falls on.Leap year calculatorCheck leap years and the rule behind the result.

Choose the right date and time calculation

Date calculations are calendar-aware: months have different lengths, leap years add a day, and business-day questions may need weekends or holidays excluded. Start with an age or date-difference tool when you know two dates. Use a deadline, countdown, week-number, or days-from-today calculator when one date is fixed and the other must be found.

Before using the result, confirm the date format, time zone, and whether the start or end date should be counted. Those small choices can change a deadline by a day, especially around midnight, daylight-saving transitions, or local public holidays.