This date calculator helps you find a new date by adding or subtracting a length of time from a date you choose. For example, if today is June 22, 2026 and you add 90 days, the result is Sunday, September 20, 2026.
It works fully in your browser, so the answer updates the moment you change any field. There is nothing to install and nothing to sign up for.
How the Date Calculator Works
You give the tool three things. A start date, an amount, and a unit of time. The calculator then moves forward or backward across the calendar and returns the matching date.
- Days move the date one day at a time.
- Weeks move the date in steps of seven days.
- Months move the date by whole calendar months, keeping the same day number where possible.
- Years move the date by whole years.
When you turn on the business days option, the calculator counts only Monday through Friday and skips Saturday and Sunday. This is useful for delivery windows, project deadlines, and payment terms.
How to Use It
Choose a Start Date
Pick the date you want to count from. The field starts on today by default, so you can begin right away.
Enter an Amount and Unit
Type a number and choose whether it means days, weeks, months, or years.
Pick a Direction
Select add to move into the future or subtract to move into the past.
Read the Result
The result date and its day of the week appear instantly. Change any field to recalculate.
What People Use It For
- Finding a deadline that is a set number of days away
- Working out a due date during pregnancy or after an appointment
- Counting contract, warranty, or return windows
- Planning travel and booking dates
- Setting reminders a fixed time before an event
- Calculating notice periods for work or rentals
Months and End of Month Dates
Adding months keeps the same day number when that day exists in the target month. If the target month is shorter, the calculator settles on the closest valid day. For example, adding one month to January 31 lands at the end of February because February has no 31st.
Adding Days Compared With Adding Business Days
Adding plain days counts every day, including weekends. Adding business days counts only working days and skips weekends. If you add ten business days to a Wednesday, the result lands two weeks later rather than ten calendar days later.