To count the days between two dates, add up the days left in the start month, every full month in between, and the days into the end month. From March 1 to December 25, 2026 there are 299 days, which is 9 months and 24 days. That count leaves out the end date; if you count both the first and the last day, the answer is 300.
Our free days between dates calculator does the counting for you: pick a start date and an end date and it shows the total number of days, plus the same span in years, months and days. This guide covers the manual method, how month lengths and leap years affect the result, and when to add a day.
How to calculate the number of days between two dates
Work through the calendar one month at a time. Count the days remaining in the start month, add the full length of each month in between, then add the day number of the end date.
Worked example: March 1 to December 25, 2026
- Days left in March after the 1st: 31 − 1 = 30.
- Full months from April to November: 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30 = 244.
- Days into December: 25.
- Total: 30 + 244 + 25 = 299 days.
The calculator gives the same 299 days and breaks it down as 0 years, 9 months and 24 days: nine whole months take you from March 1 to December 1, and 24 more days reach December 25.
Should you count the end date?
The calculator measures the gap between the two dates, so it does not count the end date. That is the right answer for nights in a hotel, days until a deadline or the length of a loan. A stay from June 12 to June 15 is 3 nights.
For anything where both the first and the last day count, such as a festival running June 12 to 15 or the days of leave you take, add 1. That festival lasts 4 days.
Years, months and days: how the breakdown works
The breakdown counts whole years first, then whole months, then the days left over. Because months have 28 to 31 days, the same number of months can hold a different number of days:
- February 1 to March 1, 2026 is 1 month, which is 28 days.
- February 1 to March 1, 2028 is also 1 month, but 29 days, because 2028 is a leap year.
- January 15 to April 15, 2026 is exactly 3 months, or 90 days.
Month-end start dates need care. January 31 to March 1, 2026 shows as 0 months and 29 days, because February has no 31st to count a whole month to. The total in days is always exact, so rely on it when the precise length matters.
Common date spans
| From | To | Total days | Years, months, days |
|---|---|---|---|
| Jan 1, 2026 | Jan 1, 2027 | 365 | 1 y, 0 m, 0 d |
| Oct 3, 2026 | Dec 25, 2026 | 83 | 0 y, 2 m, 22 d |
| Sep 14, 2026 | Dec 18, 2026 | 95 | 0 y, 3 m, 4 d |
| Feb 1, 2028 | Mar 1, 2028 | 29 | 0 y, 1 m, 0 d |
| Feb 15, 2024 | Oct 3, 2026 | 961 | 2 y, 7 m, 18 d |
Converting days into weeks and months
To turn a day count into weeks, divide by 7. The remainder is the extra days: 299 ÷ 7 = 42 weeks with 5 days left over, because 42 × 7 = 294.
Converting days into months is less exact, since no month has a fixed length. An average month is 30.44 days (365.25 ÷ 12), so 299 days is about 9.8 months. When you need calendar months, such as for a contract term or a subscription, use the years, months and days breakdown instead of dividing.
The calculator counts calendar days, weekends included. To see how a span falls across weekdays and weekends, the year calendar lays out a full year on one screen, with weekends shaded and a count of the year's weekdays and weekend days.
How to use the date difference calculator
- Open the date difference calculator. It starts with today as the start date and the same day next week as the end date, so the first result is 7 days.
- Pick the Start date. To count the days from today until an event, leave it as today.
- Pick the End date.
- Read the Total days, which does not count the end date, and the Years, Months and Days breakdown underneath.
- If the end date comes before the start date, the calculator still shows the size of the gap and warns that the end date is before the start date.
Results update as soon as you change a date, so you can step the end date forward to test different deadlines.
Practical uses and tips
- Deadlines and notice periods. Enter today and the due date to see exactly how many days remain. If the deadline day itself counts as a working day, add 1.
- Countdowns. From October 3 to December 25, 2026 there are 83 days. Change the start date as the weeks pass.
- Project timelines. Measure from a kickoff date to a launch date to report a project's length in months and days, not just a raw day count.
- Ages and anniversaries. For a person's age today, the age calculator uses the same years, months and days method and adds a countdown to the next birthday.
- Exact elapsed time. The calculator works with whole calendar dates and ignores the time of day. For a gap in hours or seconds between two moments, convert both to Unix time with the timestamp converter and subtract; 86,400 seconds make a day.
Frequently asked questions
How do I calculate the number of days between two dates?
Count the days left in the start month, add the length of each full month in between, then add the day of the end month. From March 1 to December 25, 2026 that is 30 + 244 + 25 = 299 days.
Does the days between dates calculator include the end date?
No. It counts the gap between the two dates, so June 12 to June 15 is 3 days. If you need to include both the first and the last day, add 1 to the total.
How many days are there from today until a date?
Leave the start date as today, which is the calculator's default, and pick the target date as the end date. The total days figure is the number of days remaining, not counting the target day.
How do I find the number of weeks between two dates?
Divide the total days by 7. A span of 299 days is 42 weeks and 5 days. The remainder tells you how many days are left over after the full weeks.
Does the calculator account for leap years?
Yes. It uses the real calendar, so a span that includes February 29 is one day longer. February 1 to March 1 is 28 days in 2026 and 29 days in 2028.
Can it count business days only?
No. The result is in calendar days and includes weekends and public holidays. Subtract the weekends and holidays in your range to get the number of working days.