Days Calculator

How to do days calculations

The calculator does two jobs, chosen with the Calculate buttons.

• Days between dates. Enter a From date and a To date, decide whether the last day is included, and press the button. The To date must not be earlier than the From date.
• Add days to date. Enter a starting date and a number of days. A positive number moves forward and a negative number moves back. The answer is the new date and its day of the week.

If the From date is left empty, today is used, which turns the first mode into a quick "how many days until" tool. Enter only a To date and you have a countdown.

How many days are there between two dates?

The number of days is the later date minus the earlier date. Each date is treated as a whole calendar day, so daylight saving changes never shift the count.

days between = to date − from date (+ 1 when the last day is included)

Example: 19 October 2026 to 1 January 2027 is 74 days. The calculator lists that as 74 days between the dates, 54 weekdays, a time between of 0 years, 2 months and 13 days, and 10.57 weeks (10 weeks and 4 days).

Reading the time between the dates

Besides the plain day count the calculator describes the gap as years, months and days, as a number of weeks, and as full months. These come from the calendar, not from dividing by an average.

• Time between the dates counts whole years, then whole months, then leftover days. From 19 October 2026 to 25 December 2027 it reads 1 year, 2 months, 6 days.
• Weeks in between gives the decimal number of weeks followed by the split into weeks and days: 432 days is 61.71 weeks, which is 61 weeks and 5 days.
• Months in between is the total of full months, 14 in the same example. It is shown for gaps longer than 20 days, because a shorter gap can never hold a full month.

A month is not a fixed length: January, March, May, July, August, October and December have 31 days, April, June, September and November have 30, and February has 28 or 29. In a year that is not a leap year, the gap from 31 January to 1 March is therefore 29 days and no full month, because adding a month to 31 January would land on 3 March.

Days until and days since a date

To count down, leave the From date on today and set the To date to the event. To count up, set the From date to the past event and the To date to today. Typical questions are the days until a holiday, a birthday, an exam or the end of a contract, and the days since a start date, a last payment or an anniversary.

For the days until the next birthday, the birthday calculator is quicker. For the count of calendar days with an option to include both ends, the day counter gives a shorter answer.

Adding days to a date

In the add mode the calculator moves the starting date by the number of days you give and prints the new date as year-month-day, together with the weekday. A fractional number of days is cut off toward zero, so 2.5 days means 2.

The add days calculator offers the same operation with more options. For hours and minutes instead of days, see the add hours calculator.

Dates follow the Gregorian calendar throughout, including leap years. A year is a leap year when it is divisible by 4, except for century years that are not divisible by 400.