Date Calculator
Enter a start date and a number of days, weeks, months or years to get the date that many days after (or before) it, with the day of the week.
Which tool should I use?
- Date Calculator (this page): find the date that is some days, weeks, months or years after or before a date.
- Days Between Dates Calculator: count the days, or the years, months and days, between two dates.
- Time Calculator: add and subtract hours, minutes and seconds.
- Time Converter: convert a length of time, such as seconds to hours.
- Age Calculator: find an age from a birth date.
How it works
- Days and weeks: the number of days is added or subtracted as it is (1 week = 7 days). Month lengths and leap years follow the calendar.
- Months and years: months are added or subtracted (1 year = 12 months). If the resulting month does not have the same day, the last day of that month is used, and the result tells you that it was adjusted.
- Counting the start date: this setting counts the start date as day 1 (days and weeks only). For example, 3 days after October 24 is October 27 if the start date is not counted, and October 26 if it is.
Examples
- 100 days after October 24, 2026 is February 1, 2027 (a Monday).
- 1 month after January 31, 2026 is February 28, because February has no 31st (the last day of the month).
- 1 year after February 29, 2024 (a leap day) is February 28, 2025, because 2025 has no February 29.
- 2 weeks before October 24, 2026 is October 10 (a Saturday).
Leap years
A leap year has 29 days in February. A year divisible by 4 is a leap year, except that a year divisible by 100 is not, unless it is also divisible by 400. So 2024 is a leap year, 2100 is not, and 2000 is. This calculator counts the calendar with these rules.
Notes
- Dates from January 1, 1900 to December 31, 2100 are supported. A result outside this range is shown as an error.
- Weekdays follow the Gregorian calendar. Holidays and days off are not considered, and every day is counted.
- For contracts and legal deadlines, the way the first day is counted depends on the document or the law, so check the wording or ask a professional.
Frequently asked questions
What is the date 100 days from today?
Enter today's date as the start date, 100 as the number, and Days as the unit. The result shows the date and the day of the week.
Why is 1 month after January 31 February 28?
February has no 31st. When you add months or years and the resulting month does not have the same day, the last day of that month is used (February 29 in a leap year). If this happens, a note appears under the result.
Are 30 days and 1 month the same?
Not always. 30 days counts days, while 1 month moves the month forward by one. In a month that does not have 30 days, the dates differ by one or two days.
How is the day of the week found?
The calculator counts days from a fixed starting day and uses the remainder after dividing by 7. The weekday of the start date is also shown near the result.