How to Calculate Days Between Two Dates (Inclusive or Not)

The short answer

To find the number of days between two dates, subtract the start date from the end date. From 1 January 2026 to 11 October 2026 is 283 days. If you need to count both the first and the last day (for example, the length of a leave period or a hotel stay counted in days), add 1: 284 days.

The Date Difference Calculator gives the difference in days, weeks, months, years, hours and minutes as soon as you pick two dates.

Exclusive vs inclusive: the off-by-one question

This is where most date counting goes wrong. There are two different questions:

• "How many days from A to B?" This is the gap between the dates. Monday to Friday is 4 days. This is what the calculator shows, and what most date functions return.
• "How many days are there from A to B, counting both?" This counts calendar days in a range. Monday to Friday is 5 days, because Monday, Tuesday, Wednesday, Thursday and Friday are all included.

Situation	Usually counted as	Example: 1 to 10 March
Time elapsed, age, "days since"	Exclusive (end − start)	9 days
Leave days, event days, rental days	Inclusive (end − start + 1)	10 days
Hotel nights	Exclusive (nights between check-in and check-out)	9 nights
Deadlines "within 30 days"	Depends on the rule or contract	Check the wording

Rule of thumb: if every date in the range is a "day used", add 1. If you are measuring the time between two moments, do not.

For legal, tax or contract deadlines, the counting rule is set by the relevant law, contract or authority, and some rules exclude the first day or extend a deadline that falls on a holiday. Always follow the wording that applies to you.

Using the Date Difference Calculator

Open the Date Difference Calculator.

Pick the Start date and the End date. The end date defaults to today.

Read the results in six boxes: Days, Weeks, Months, Years, Hours and Minutes.

A few details about how the results are calculated:

• Order does not matter. If the end date is earlier than the start date, the calculator swaps them and shows a positive difference.
• Days is the exact gap between the two dates (exclusive). Add 1 yourself if you need an inclusive count.
• Weeks is whole weeks, rounded down. 283 days shows as 40 weeks (40 weeks and 3 days).
• Months is an approximation: days divided by 30.44 (the average month length), rounded to the nearest whole number. 283 days shows as 9 months.
• Years is days divided by 365.25, shown to two decimals. 283 days shows as 0.77 years.

If you need an exact "X years, Y months, Z days" breakdown, such as for a birthday or age on a cut-off date, use the Age Calculator instead, because calendar months have different lengths and an average cannot give an exact answer.

Leap years change the answer

A leap year adds 29 February, so any range that crosses it has one more day:

• 1 January 2024 to 1 January 2025 = 366 days (2024 was a leap year).
• 1 January 2026 to 1 January 2027 = 365 days.
• 1 February 2026 to 1 March 2026 = 28 days. The same range in 2028 is 29 days.

Leap years are years divisible by 4, except century years that are not divisible by 400. So 2000 was a leap year, 2100 will not be. The calculator handles this automatically because it uses real calendar dates.

Worked examples

Days until a deadline. Today is 11 October 2026 and a project is due on 31 December 2026. Enter both dates: 81 days remain. If the due date itself is a working day you can use, you have 82 calendar days including today and the due date.

Notice period end date. If you resign on 11 October 2026 with a 90-day notice period, the date 90 days later is 9 January 2027. Check your contract to see whether the resignation day itself counts as day 1. If it does, your last day is 8 January 2027.

Financial year length. 1 April 2026 to 31 March 2027 gives 364 days as a gap. Counting both days, the financial year has 365 days.

Counting only working days

The days shown above are calendar days, including weekends and holidays. For business deadlines, salary calculations or delivery estimates, you usually need working days. Use the Working Days Calculator for that and check how it treats public holidays in your region. The guide How to Calculate Working Days Between Two Dates explains the method.

Days, hours and minutes

The Hours and Minutes boxes are the total gap converted into those units. For two dates (with no time of day), this is simply days × 24 and days × 1,440. 283 days is 6,792 hours or 407,520 minutes. If you need the gap between two exact times, including hours and minutes, a timestamp is easier: see Unix Timestamps Explained.

Doing it by hand (or in a spreadsheet)

• By hand: count the remaining days in the start month, add the full months in between, then add the days in the end month. From 15 March to 10 May: 16 days left in March (31 − 15), 30 in April, 10 in May = 56 days.
• In Excel or Google Sheets: put the dates in two cells and subtract: =B1-A1. Format the result as a number. Add +1 for an inclusive count. The function =DAYS(B1, A1) returns the same result.

Common mistakes

• Forgetting to add 1 when every day in the range counts (leave, events).
• Treating "months" as exact. 30.44 is an average; February and July differ by 3 days.
• Mixing up date formats. 03/04/2026 is 3 April in India and the UK but March 4 in the US. The calculator uses a date picker, which avoids this.
• Forgetting leap years when counting across February by hand.