Date Calculator
Count the days between two dates, or find the date that falls a set number of days, weeks, months or years before or after another.
Date Calculator
How the day count works
The calculator subtracts the start date from the end date in whole calendar days, counting every leap day along the way. The result is broken down several ways:
- Years, months and days: whole calendar months first, then the leftover days. March 15 to May 20 is 2 months and 5 days.
- Weeks and days: the total divided by 7, with the remainder in days.
- Business days: Monday to Friday only, with no allowance for holidays.
Common uses
Deadlines and notice periods
Need to know the date 30, 60 or 90 days from today? Use Add or subtract. Contracts often say “within 30 days”, which usually means 30 calendar days, not business days. Read the wording.
Countdowns
Set the start date to today and the end date to a birthday, holiday, wedding or due date to see how many days are left.
Age in days
Enter a birth date and today's date. Someone born on June 1, 2000 was 9,287 days old on November 4, 2025.
Days in each month
January, March, May, July, August, October and December have 31 days. April, June, September and November have 30. February has 28, or 29 in a leap year. A year is a leap year if it is divisible by 4, except years divisible by 100 unless they are also divisible by 400. So 2000 was a leap year, but 1900 was not.
Frequently asked questions
How many days are between two dates?
Subtract the earlier date from the later one. The calculator counts calendar days and does not include the end date unless you tick “Include the end date”. From January 1 to January 31 is 30 days, or 31 days counting both ends.
Should I include the end date?
Include it when both the first and last day count, such as a hotel booking that you count by nights versus days, a leave of absence, or a contract that runs “from” one date “through” another. Leave it off for elapsed time, such as someone's age in days.
How are business days counted?
Business days are Monday through Friday. The calculator does not know your public holidays, so subtract any that fall in the range.
What happens when I add a month to January 31?
There is no February 31, so the result moves back to the last day of February (28th, or 29th in a leap year). Most banks and contracts use the same rule.
Does daylight saving time affect the count?
No. The calculator works with whole calendar days, so clock changes never add or remove a day.
See also
- Time Duration Calculator: Hours and minutes between two times, overnight shifts and breaks included.
- Percentage Calculator: Percent of a number, percent change, and increase or decrease by a percent.
- Amortization Calculator: Monthly payment, payoff date and full schedule, with extra payments.
Last updated: November 4, 2026