Date Calculator

What this tool does

This date calculator handles the two questions people ask most: “What date is N days from now?” and “How many days are between these two dates?” You can add or subtract days, weeks, months, or years. There’s also a business-day mode that skips weekends for schedules, shipping estimates, and workback plans. Everything runs in your browser and uses UTC behind the scenes, so daylight-saving changes and local time zones don’t quietly shift your answer.

The output is built for copy-paste. You’ll see a friendly date, the exact ISO format, and the weekday. For differences, you’ll get a total day count, business-day count, and the calendar span expressed as years, months, and days. If you need more context once you have a result, jump over to our Time Zone Calculator to convert the date and time, set a reminder with the Countdown Calculator, or sanity-check an age or anniversary with the Age Calculator.

How to use

1. Pick a Mode: Add/Subtract or Difference.
2. For Add/Subtract: choose the start date, pick Add or Subtract, enter an amount, then select a unit (days, weeks, months, years, or business days).
3. For Difference: set the From and To dates. We’ll compute totals in both directions automatically and display them consistently.
4. Click Calculate. Use Download CSV to save a simple record for project files, tickets, or emails.

Tips: business days skip Saturdays and Sundays only. If you need holidays excluded, subtract them manually from the result. When adding months or years, the calculator clamps to valid calendar dates (for example, adding one month to January 31 lands on February 28 or 29).

What you’ll see

• Result: the final date in a readable format, the ISO string, and the weekday. ISO is handy for spreadsheets and logs.
• Extras: absolute days, business-day count (Mon–Fri), and a calendar span in Y/M/D that respects varying month lengths and leap years.
• Months/years use end-of-month clamping, so longer months don’t create invalid dates.

Real-world planning often mixes both modes. For example, you might add 90 calendar days to a contract date, then check the business-day count between now and the deadline. Use whichever view helps you make the call, then export the CSV and attach it where it needs to live.

FAQ