Date Time

Date and time math: how many days between two dates, what day of the week a date falls on, what date it will be in 30 or 90 days, week numbers and countdowns.

116 free tools in this category. See every tool on Lelifi.

• 1 Hour From Now1 hour from now is the same minute on the next hour. See the 12 o'clock wrap, th
• 1 Month Notice Period CalculatorEnter the day you hand in notice to get the last day of a one month period, the
• 1/8 Mile Time CalculatorTurn an eighth mile ET and trap speed into average speed, acceleration, a quarte
• 10 Hours From Now10 hours from now is your clock plus ten hours. See the sleep window it builds,
• 10 Minutes Ago10 minutes ago means the clock minus ten minutes, borrowing an hour when minutes
• 10 Weeks Ago From TodaySee the exact date 10 weeks ago from today, the weekday it landed on, the 70 day
• 11 Hours From Now11 hours from now is your clock plus eleven hours. See the shift hours it covers
• 12 Hours From Now12 hours from now is half a day later: the minutes stay put and AM flips to PM.
• 120 Days From TodaySee the exact date 120 days from today or any start date, the weekday it lands o
• 13 Hours From Now13 hours from now is the same clock reading one hour on, with the AM or PM tag r
• 14 Days From TodaySee the exact date 14 days from today, the weekday it lands on, when 14 business
• 15 Hours From Now15 hours from now is 900 minutes ahead. See the clock time, then run it backward
• 16 Hours From Now16 hours from now is 960 minutes ahead. See the clock time, the sleep window it
• 17 Hours From Now17 hours from now is 1,020 minutes ahead, or 70.83 percent of a day. See the arr
• 18 Hours From Now18 hours from now is 1,080 minutes ahead, three quarters of a day. Get the clock
• 180 Days From TodaySee the exact date 180 days from today or any start date, the weekday it lands o
• 183 Day Rule CalculatorEnter your days in the US for the last three years and get the weighted 183 day
• 19 Hours From Now19 hours from now is 1,140 minutes ahead, or 79.17 percent of a day. See the arr
• 2 Hours From Now2 hours from now is 120 minutes ahead, or 8.33 percent of a day. See the arrival
• 20 Hours From Now20 hours from now is 1,200 minutes ahead, or 83.33 percent of a day. See the arr
• 21 Days From TodaySee the exact date 21 days from today, the weekday it lands on, the hours and mi
• 28 Days From TodaySee the exact date 28 days from today, which is always the same weekday, plus 28
• 30 Days From TodaySee the exact date 30 days from today, plus 30 business days, the day of the wee
• 45 Days From TodaySee the exact date 45 days from today or any start date, the weekday, 45 busines
• 60 Days From Today CalculatorSee the date 60 days from today and 60 days back, the weekday, the month and yea
• 90 Days From Today CalculatorSee the exact date 90 days from today, plus 90 business days, weeks and a custom
• Add Days CalculatorAdd or subtract days from several start dates at once. Get the new date, weekday
• Add Days to a DateFree date calculator: add or subtract any number of days from a date and see the
• Add Time CalculatorAdd hours, minutes and seconds for any list of spans, see the total in decimal h
• Age CalculatorFind your exact age in years, months, days, weeks, hours and minutes from your d
• Age Difference CalculatorEnter two birthdays and get the exact age gap in years, months and days, plus to
• Age to Birthday CalculatorFind your birth date range from current age, or calculate exact dates and days r
• Anniversary CalculatorCount how long you have been married in years, months and days, see the total da
• Average Time CalculatorEnter several h:m:s timings and get the average, total, median, fastest and slow
• Baby Age CalculatorCalculate your baby's age in months, weeks, and days. Get adjusted age for babie
• Birth Year CalculatorTurn your age into a birth year, with the birthday cutoff handled, plus the gene
• Birthday Countdown CalculatorSee exactly how many days, weeks and hours are left until your next birthday, th
• Business Days CalculatorCount business days between two dates, excluding weekends and optional US federa
• Calendar CalculatorDraw any month as a full calendar grid with ISO week numbers and federal holiday
• Calendar Countdown CalculatorCount the days, weeks and months between two dates, see how including the end da
• Chronological Age CalculatorTurn a birth date and any reference date into exact chronological age in years,
• Countdown Timer CalculatorSet a countdown by length or by end time. See the total in seconds, the hh:mm:ss
• Cyber Monday Date CalculatorCyber Monday 2026 is November 30, four days after Thanksgiving. Get the date for
• Date CalculatorBoth directions of date math in one tool: years, months and days between two dat
• Date Countdown CalculatorCount the days, weeks, weekdays and hours left until any target date, with inclu
• Date of Birth CalculatorWork out an exact age from a birth date, or turn an age back into the birth date
• Day CounterCount the days between two dates, with or without the first day. Get calendar da
• Day of the Week CalculatorGet the weekday for any date, list every Monday in a month, or move a due date o
• Day of the YearType any date and get its day number out of 365 or 366, the days left in the yea
• Days Between DatesFree days between dates calculator. Pick two dates and get the exact day count,
• Days Left in the YearCount the days left in the year from any date, see the day number, the weekdays
• Days Old CalculatorFind how many days old you are from any start date, with weeks, hours, minutes a
• Days Since CalculatorCount the days, weeks and weekdays since any event date, with day zero rules, re
• Days Together CalculatorCount how long you have been together from your first date: days, weeks, months
• Days Until ChristmasCount the days until Christmas 2026, see how many shopping Saturdays are left, a
• Days Until EasterCount the days until Easter 2027 on March 28, see Ash Wednesday and Good Friday
• Days Until Fall 2027: Countdown to the September EquinoxCount the days until fall 2027 on September 23, compare the September 1 and equi
• Days Until HalloweenCount the days until Halloween 2026, see the weekends left, and work out how man
• Days Until My BirthdayFree days-until-my-birthday calculator: enter your birth date to see the countdo
• Days Until New Year's DayFind out exactly how many days, weeks, hours, and business days remain until New
• Days Until SummerCount the days until summer 2027 on June 21, compare the June 1 and solstice sta
• Days Until Tax DeadlineFree countdown to Tax Day 2027: see how many days, weeks and business days are l
• Days Until ThanksgivingCount the days until Thanksgiving, November 26 in 2026, plus Black Friday, Cyber
• Days Until Valentine's DayValentine's Day 2027 lands on Sunday, February 14, which is 112 days from Octobe
• Doubling Time CalculatorFind how long a value takes to double from its growth rate, work back from a dou
• Easter Date CalculatorFind the date of Easter for any year from 1583 to 4099, plus Ash Wednesday, Good
• Easter Date and the Computus That Sets ItEaster falls on April 5 in 2026. See how the Meeus/Jones/Butcher computus fixes
• Elapsed Time CalculatorFind the time between two clock readings in hours, minutes and seconds, plus tot
• Half Birthday CalculatorEnter a birth date to get the exact half birthday, the weekday it lands on, a co
• Hour Countdown CalculatorCalculate remaining hours, minutes, and seconds to any target time or deadline.
• Hours CalculatorWork out the hours between two clock times, subtract a lunch break, get decimal
• Hours Worked CalculatorEnter your clock in and out times, an unpaid break and your rounding rule for pa
• How Many Days Have I Been Alive?Enter your birth date and see exactly how many days you have been alive, plus ho
• How Many Days Until CalculatorCount the days until any date, with or without today counted, plus the weeks, mo
• How Many Days Until My Birthday?Answer how many days until my birthday in one click. Get the count in days, week
• Lead Time CalculatorFree lead time calculator: add processing, transit and buffer days to an order d
• Leap Year CalculatorCheck any year against the 4, 100 and 400 rules, see the next leap year, count F
• Marriage CalculatorSee how long you have been married: enter your wedding date and today and get th
• Military Time ConverterConvert 12-hour clock times to military time and back, read them out loud, turn
• Month CalculatorCount whole months between two dates or add and subtract months, with end-of-mon
• Month Counter for Calendar Months and DaysCount calendar months and leftover days between two dates, with end-of-month and
• Months Between Dates CalculatorFind how many months are between two dates. Get whole calendar months, a years-m
• Moon Phase CalculatorSee the moon phase, percentage lit and moon age for any date, plus the next new
• New Year's CountdownCount down to midnight in your own time zone: from October 18, 2026 the new year
• Pregnancy Countdown CalculatorTrack your pregnancy countdown by due date or last period. Calculate days left,
• Reading Time CalculatorEstimate how long a text takes to read. Paste your text or enter a word count, p
• Speed Distance Time CalculatorSolve for distance, speed or time from the other two, convert mph, km/h, m/s and
• StopwatchA free online stopwatch with start, stop, lap and reset. It reads in hours, minu
• Sunrise and Sunset CalculatorGet sunrise, sunset, day length and all three twilight times for any latitude an
• Thanksgiving Date and Planning CalculatorFind the Thanksgiving date for any year, count the days remaining, and plan turk
• Time CalculatorAdd or subtract hours, minutes and seconds across several time spans. Get the to
• Time Difference CalculatorFind the exact hour gap between two time zones on any date, see what 9 a.m. East
• Time Dilation CalculatorEnter a speed and an elapsed time to get the Lorentz factor, the clock reading o
• Time Duration CalculatorEnter a start and end date and time to get the exact duration in days, hours and
• Time Span CalculatorEnter two dates and times to see one span in years, months, days, weeks, hours,
• Time Until CalculatorCount the time until any date and clock time. Get a live countdown in days, hour
• Time Zone CalculatorConvert a local date and time between 17 world zones through UTC, with 2026 dayl
• Time to Hours CalculatorConvert any stretch of time to hours: minutes, seconds, days and clock times bec
• Time to Minutes CalculatorTurn 2 hours 15 minutes 30 seconds into 135.5 minutes. Convert hh:mm:ss to total
• Today's DateToday's date with the weekday, the day number out of 365 or 366, the ISO week, t
• Travel Time CalculatorEnter distance, average speed and stops to get driving time, door to door time,
• Vacation Countdown CalculatorCalculate days, workdays, weekends, and hours until your vacation departure. Tra
• Week CalculatorCount the whole weeks and leftover days between two dates, add or subtract weeks
• Week Number 2026Find the week number for any date in 2026. See the ISO week, the Monday and Sund
• Week Number CalculatorFind the ISO 8601 week number for any date, or the Monday to Sunday dates for an
• Weekday CalculatorFind the weekday for any date, plus the day of the year, ISO week and leap year
• Weeks Between Dates CalculatorFind the weeks and days between any two dates, with working days, weekend days,
• Weeks CalculatorCount the weeks between two dates, add or subtract weeks, and see why a year is
• Weeks Left in the YearSee how many weeks are left in 2026 from any date, which ISO week you are in, th
• What Day Is It?Find out what day of the week any date falls on, its day of the year, the ISO we
• What Day Was I Born?Enter a birth date to see the weekday, the day of the year, the week number, and
• What Day Will It Be in 100 Days?Find the exact date and weekday 100 days from today or from any start date. Incl
• Work Hours CalculatorEnter clock-in, clock-out and unpaid lunch per day to get decimal hours, weekly
• Working Days CalculatorCount the working days between two dates, skip weekends and federal holidays, th
• Years Ago CalculatorFind the date a number of years back, or the whole years between two dates, with
• Years Between Two Dates CalculatorFree years between two dates calculator: enter any two dates and see the exact y

Date math is simple until you have to do it, and then the off-by-one question shows up. Does a 30-day return window close on day 30 or the day after? Do you count weekends? These tools give the exact answer and show the countdown, the weekday and the week number so you can plan around it.

The off-by-one trap

By default a days-between count does not include the end date, so it answers how much time has passed. June 1 to July 1 is 30 days. A store that counts the purchase day as day 1 would close that window on June 30 instead. The subtraction never changes, only the rule about which day counts as the first one.

• Return windows: a laptop bought June 1 with a 30-day policy is usually returnable through July 1.
• Business days: the calculator skips weekends and optional US federal holidays, which matters for shipping, contracts and pay periods.
• Tax Day: the countdown shows the days, weeks and business days left until April 15, plus other IRS filing dates.
• Milestones: a days-together count turns a first date into days, weeks, months and the next anniversary.

A span of 90 days is 12 weeks and 6 days, not a clean 13 weeks, which is why a 90-day plan and a 13-week plan end on different days. When a deadline has legal or financial weight, confirm the rule in the document itself.