Days Between Two Dates Calculator

How does this day counter work?

To find how many days are between two dates, the calculator turns each date into a day number and subtracts one from the other, so the answer never depends on your time zone or the time of day.

The end date isn't counted unless you switch on Include the end date, which adds one day. Leap years are built in. Months are counted as whole calendar months from the start date, and when a month is too short the count stops on its last day, so January 31 plus one month lands on the last day of February. Hours and minutes are the days multiplied by 24 and by 1,440, which keeps a span that crosses a daylight saving change at 24 hours a day.

How do you count the days between dates by hand?

To calculate the days between two dates by hand, count the days left in the start month, add the full months in between, then add the days into the end month. Here is March 15 to July 4:

1. March has 31 days, so 16 days remain after March 15.
2. April, May and June add 30, 31 and 30 days, which is 91.
3. July 4 is 4 days into July.

That's 16 + 91 + 4 = 111 days, in any year.

Day-of-year numbers give you a faster check. In a common year March 15 is day 74 and July 4 is day 185, and 185 minus 74 is 111. When the dates fall in different years, subtract the start date's day number from the length of its year, add 365 or 366 for each full year in between, then add the end date's day number.

How many days are in each month?

Seven months have 31 days, four have 30, and February has 28, or 29 in a leap year. The old rhyme still works: thirty days hath September, April, June and November.

The last column gives the day of the year each month starts on in a common year, which is what you need for the day-number check above. From March onward, add 1 in a leap year.

Should you count the end date?

Count the end date when the last day is used in full, as with vacation days or a three-day festival, and leave it out when you're measuring the time between two moments, as with hotel nights or someone's age. Leaving it out is the default here, and it's what spreadsheet subtraction does too.

Deadlines are where a one-day slip costs the most. Courts, contracts and immigration offices each define how days are counted, including whether the first day counts and what happens when the last day lands on a weekend, so check the governing rule before you rely on any calculator, this one included.

How many weeks, months and years are between two dates?

To express the duration between two dates in weeks, divide the day count by 7 and keep the remainder; for months and years, count whole calendar months from the start date, then the days left over. So 111 days is 15 weeks and 6 days, and April 15 to July 20 is 3 months and 5 days, or 96 days.

Months need that approach because they run from 28 to 31 days. Divide 96 days by 30 and you get 3.2 months, a number that won't tell you which date you land on. A full year from any date ends on the same date a year later: 365 days, or 366 when February 29 falls in between.

For a sense of scale, 100 days is 14 weeks and 2 days, 365 days is 52 weeks and 1 day, and 1,000 days is a little under 2 years and 9 months. If you need the time between two dates in hours, multiply the days by 24.

How do you count the days until or since a date?

Press Today on either date and the calculator turns into a countdown or a count-up. Put today first and a future date second to see how many days are left, or a past date first and today second to see how many days have passed. From December 1, Christmas Day is 24 days away.

Leave Include the end date off for countdowns, so the big day itself isn't counted as a day of waiting. And remember that today means today on your device: Tokyo is already on tomorrow's date for much of the day in New York. To find the date a set number of days from today instead, use the date calculator.

What's the difference between calendar days and business days?

Calendar days include every day on the calendar, while business days skip weekends and public holidays. Any Monday to the Monday two weeks later is 14 calendar days but only 10 business days.

Contracts, shipping estimates and government forms usually say which kind they mean, and the gap grows quickly: 30 business days is roughly six weeks on the calendar. The calculator shows how many weekdays your span contains. To leave out holidays as well, or to find the date a set number of business days ahead, use the business days calculator.

How do leap years change the count?

A leap year adds February 29, so any span that crosses it is one day longer: February 1 to March 1 is 28 days in a common year and 29 in a leap year.

A year is a leap year if it divides evenly by 4, unless it's a century year, which also has to divide by 400. That's why 2000 was a leap year and 2100 won't be.

The calculator accounts for leap years automatically and tells you when February 29 falls inside your dates. People born on February 29 usually celebrate on February 28 or March 1 in other years, and which date counts legally depends on where you live.

How do you count days in Excel and Google Sheets?

Put the start date in A2 and the end date in B2, then use =B2-A2; for March 15 to July 4 it returns 111. =DAYS(B2,A2) gives the same answer with the end date first, and adding 1 to either formula counts both dates. If the result shows up as a date, change the cell format to Number. The calculator above writes the matching formula for whatever dates you enter.

For whole months or years, =DATEDIF(A2,B2,"m") and =DATEDIF(A2,B2,"y") count complete months and years. They can disagree with the calculator around month ends, because DATEDIF won't count January 31 to February 28 as a full month. For business days, =NETWORKDAYS(A2,B2) skips weekends, and a range of holiday dates can go in as a third argument, as in =NETWORKDAYS(A2,B2,E2:E12). NETWORKDAYS counts both the start and the end date, so it usually returns one more than the business days calculator does.

How do date formats cause counting mistakes?

Reading a date in the wrong format causes the biggest errors: 03/04 means March 4 in the United States but April 3 in the UK, most of Europe and Australia. The ISO 8601 format puts the year first, then the month and the day, so it reads the same everywhere, and the calculator removes any doubt by writing each date out under its box.

A few other slips come up again and again:

• Counting the end date when you shouldn't, or leaving it out when you should. The answer is off by exactly one.
• Mixing calendar days and business days in the same plan.
• Typing two-digit years. Spreadsheets guess the century, so a year typed as 30 can become 1930 in one program and 2030 in another.
• Ignoring time zones. A deadline of midnight in California has already passed in London.

More questions about counting days