📅 Date Calculator

Add or subtract time from any date, or find the difference between two dates.

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📅 Date Calculator

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Related Guide
Date Math: Adding, Subtracting and Counting Days Between Dates
Why month lengths and leap years make date math tricky by hand.
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What is the Date Calculator?

This tool has two modes: Add/Subtract, which moves a start date forward or backward by a chosen number of days, months, and years, and Difference, which counts the exact days, weeks, and approximate months and years between two dates. Both handle leap years and varying month lengths automatically, so you don't have to count on a calendar by hand.

How to Use It

In Add/Subtract, pick a start date, choose Add or Subtract, enter days, months, and/or years, and click Calculate to see the resulting date and its day of the week. In Difference, enter a start and end date and click Calculate to see the total days, weeks, and approximate months/years between them.

When to Use It

Use it to work out a contract or lease end date, a project deadline a set number of weeks out, a billing cycle renewal date, or how many days remain until an event. It's also useful for finding what date it was or will be a specific number of days in the past or future, such as "90 days from today."

Who Benefits

Project managers tracking deadlines, HR and legal staff calculating contract or notice periods, and anyone planning an event or trip who needs to count out dates accurately instead of counting days on a calendar.

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Frequently Asked Questions

Set the start date to today, choose Add, enter 30, 60, or 90 in the Days field, and click Calculate. These intervals are commonly needed for contract deadlines, invoice payment terms, and return windows, and the calculator accounts for the exact number of days in each month.
No, it counts all calendar days between the two dates. For a business-days-only count that excludes weekends (and optionally holidays), use the Days Between Dates calculator instead.
Because months and years don't have a fixed number of days — a month can be 28 to 31 days and a year can be 365 or 366. The calculator converts the exact day count using average lengths (30.44 days/month, 365.25 days/year) to give you a readable estimate alongside the exact day and week totals.