Should you include the end date?
The standard answer to "how many days between two dates" is the difference: subtract the earlier date from the later one. From Monday to Friday of the same week is 4 days. That is the right count for "how many days until", ages, interest periods and most deadlines.
Sometimes you want to count both the first and the last day: a hotel guest arriving Monday and leaving Friday is billed for 4 nights, but a festival that runs Monday through Friday lasts 5 days. Choose "include the end date" for counts like that; it adds exactly one day.
Months and years are not fixed lengths
Days and weeks are exact, but a month can be 28 to 31 days and a year 365 or 366. So the calculator counts whole calendar months first — the most months you can step forward from the start date without passing the end date — then reports the days left over. From January 15 to March 20 is 2 months and 5 days.
If the start date is the 29th, 30th or 31st, stepping forward a month can land on a day that doesn't exist. The calculator uses the month-end rule: January 31 plus 1 month is the last day of February. So January 31 to February 28, 2026 counts as exactly 1 month.
Leap days are counted where they fall: a span that crosses February 29 is one day longer than the same span in a common year.
Weekdays versus business days
The weekday count here is every Monday through Friday in the span, counted on the same basis as the total (so the end date is counted only if you include it). It does not remove public holidays, because which holidays apply depends on your employer, bank or court.
For US federal holidays, use the business days calculator, which removes the 11 federal holidays and handles the rules for holidays that fall on a weekend.
How the counts are calculated
Total days = end date − start date (+ 1 if the end date is included)Weeks = floor(total days ÷ 7), remaining days = total days mod 7Months = the largest n where start date + n months ≤ end date; days = end date − (start date + n months)- Dates are counted as whole calendar days in your local calendar, so daylight saving time changes never add or lose a day.
- Years = floor(months ÷ 12), with the remaining months shown separately.
Worked example
- From Thursday, January 1, 2026 to Friday, December 25, 2026, not including the end date.
- Total days: January 1 is day 1 of the year and December 25 is day 359 in a common year, so the difference is 359 − 1 = 358 days.
- In weeks: 358 ÷ 7 = 51 remainder 1, so 51 weeks and 1 day.
- In months: January 1 plus 11 months is December 1, and from December 1 to December 25 is 24 more days, so 11 months and 24 days.
- Weekdays: 256 of the 358 days fall Monday to Friday, leaving 102 weekend days.
- Including the end date adds Friday, December 25: 359 days and 257 weekdays.
Frequently asked questions
How many days are there between two dates?
Subtract the earlier date from the later one. Counting by hand, count the days remaining in the first month, add the full months in between, then add the day number of the final date. This calculator does it exactly, including leap years.
How many days are in 2026?
365. 2026 is not a leap year; the next leap year is 2028. A common year has 52 weeks and 1 day, and 2026 has 261 weekdays.
Why does my count differ by one from another calculator?
Almost always because one counts the end date and the other doesn't. From the 1st to the 10th is 9 days as a difference, or 10 days if both the 1st and the 10th are counted.
How many weeks are between two dates?
Divide the number of days by 7. The calculator shows whole weeks plus the leftover days, for example 358 days is 51 weeks and 1 day.
Does daylight saving time change the count?
No. The calculator counts calendar days, not 24-hour blocks, so the 23-hour and 25-hour days when clocks change still count as one day each.
Sources
Last reviewed for 2026. How we calculate.