Date Calculator
Add or subtract dates, compare two dates, and calculate weekday deadlines from any start date.
What Is a Date Calculator?
A date calculator turns a time question into a specific calendar date. Instead of counting days on a calendar, you can add or subtract days, weeks, or months from any start date and see the result immediately. It is useful whenever a plan starts with a phrase like "two weeks after launch" or "30 days before the deadline."
This online date calculator also compares two dates and counts weekdays. That makes it useful for setting project milestones, scheduling follow-ups, estimating a review window, and checking how long a trip, course, or contract lasts. Every result includes the full date and day of the week, so it is ready to use in your schedule.
How to Use This Date Calculator
Pick the calculation that matches the question you need to answer. Results update as you change the dates or amount, and you can copy either the result or a shareable link when you are finished.
- 1
Choose a calculation type
Use Date Add / Subtract to move forward or backward from a date, Date Difference to measure the time between two dates, or Weekdays to count Monday through Friday.
- 2
Enter the dates and amount
Select a start date, then enter the number of days, weeks, or months you want to add or subtract. For a date difference, select the start and end dates instead.
- 3
Use the result in your plan
Copy the exact date for an email or calendar, or copy the link to return to the same calculation later.
What Can This Date Calculator Help With?
Plan deadlines
Calculate a due date from a project start date, a review date after a milestone, or the date to send a reminder before an event.
Compare date ranges
See the total calendar days, full weeks, and remaining days between a start date and an end date without doing the math by hand.
Count weekday deadlines
Find a date after a set number of weekdays when a timeline skips Saturday and Sunday. Public holidays are not excluded from this calculation.
Date Calculator FAQs
Can I add weeks or months to a date?
Yes. Select Date Add / Subtract, choose Add, then enter the amount and select days, weeks, or months. The date calculator handles month and year boundaries automatically.
What is the difference between calendar days and weekdays?
Calendar days include every day of the week. The Weekdays mode skips Saturdays and Sundays, but it does not currently remove public holidays.
Can I calculate a date from today?
Yes. Select Today next to the start date, then add or subtract the time you need. For a quick weekly lookup, you can also check 1 week from now or 12 weeks from now.