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Time and Date Calculators

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Pick the date calculator that matches what you already know. Two dates go into the days between dates calculator, and one date plus a number of days goes into add days. The calculators take your own dates and times. The ready-made countdowns near the bottom are already set for holidays and common dates. Hours worked and time cards live on the work hours pages.

Date math

Date differenceCalendar days between two dates, optional include-end. Add daysMove a calendar date by days, weeks, months, or years. Days from today30, 60, 90 days and other offsets from today. Business daysWeekdays only, optional US federal holidays. Age calculatorYears, months, days, and days until the next birthday. Add timeAdd or subtract hours from a clock time. Week numberISO week and US Sunday-start week of year.

Countdowns and time left

Days untilCountdown from today, weeks remaining, year left. Countdown timerYour own live countdown to any date and time, with a share link. Holiday countdownUpcoming holidays with days and weeks left. Hours untilHours and minutes to a date and time. Weeks untilWhole weeks from today to any date. Months untilWhole calendar months until a date. Days left in the yearCalendar days remaining until 31 December. Weeks left in the yearWeeks and days remaining until 31 December. Months leftFull months still ahead this year. Year progressPercent of the year already complete. Work days leftWeekdays left this month and year.

Time zones and conversions

Time zoneConvert a date and time between cities. Unix timestampEpoch seconds or milliseconds to a readable date. Hours to minutesHours × 60, or minutes back to hours.

Calendar and sky facts

What week is it?Today's ISO and US week number, with this week's dates. What quarter is it?Current quarter, days left and every quarter's dates. Next full moonToday's moon phase and the next 12 full moons. Leap yearsIs this year a leap year, and the next one. Clocks go forwardWhen daylight saving time starts in the US and Europe. Clocks go backWhen daylight saving time ends, and the extra hour.

Life and age

Death clockStatistical time left as a live countdown, with the range. Weeks until you dieYour life in weeks on one chart, with the odds for each week ahead. Life expectancyStatistical weeks remaining. Not medical advice. Life expectancy by ageYears left at every age from 0 to 100, CDC 2024. Life milestones10,000 days old, 1 billion seconds and more.

Ready-made countdowns

Every calendar date, month, holiday and season, counted to its next occurrence.

Days untilAny date, month, holiday or season. Weeks untilWhole weeks plus leftover days. Months untilCalendar months plus leftover days. Weekends untilSaturdays left before a date or holiday. Business days untilWeekdays minus US federal holidays. Days left in a yearAny year from 2026, with business days by month. N days from todayThe date 1 to 1,000 days ahead. N days agoThe date 1 to 1,000 days back.

For punch in/out hours, start at the work hours tools.

Time and date questions

How do I count the days between two dates?

Take the earlier date away from the later one. From March 1 to March 31 is 30 days, because the start day is left out. Add 1 if you count both days. The days between dates calculator can do it either way.

How do I count business days?

Count Monday to Friday, then remove any public holiday that lands on a weekday. The business days calculator knows the holidays for the US, UK, Canada, Australia and Ireland.

What week number is it?

That depends on the system. ISO weeks start on Monday, and week 1 holds the first Thursday of the year. The week number calculator gives the ISO week and the US week for any date.

Cite this page

APA: ClockTotals. (2026, October 16). Time and Date Calculators. https://clocktotals.com/time-date/

MLA: “Time and Date Calculators.” ClockTotals, 16 Oct. 2026, clocktotals.com/time-date/.

Link (HTML): <a href="https://clocktotals.com/time-date/">Time and Date Calculators</a>