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Free Online Tool

Date Calculator

Calculate exact days between two calendar dates, add or subtract business days and calendar days, determine week numbers, and execute calendar math. Free online tool for calculating date ranges, project deadlines, and period intervals.

Interactive Date Calculator

Other

Duration Results

Difference in Days:
30 Days
Weeks Between:4.3 wks
Months Between:1.0 mos

How to Use the Date Calculator

  • Select your starting calendar date.
  • Enter the exact number of days, weeks, or months to add or subtract.
  • View the calculated destination target date along with day of the week, total calendar days, and total weeks.

Formula & Calculation Methodology

Duration = Target Date - Start Date (in milliseconds / 86,400,000 days). Target Date = Start Date ± N Days.

Our mathematical algorithms adhere to standard scientific and financial guidelines to deliver maximum accuracy.

Frequently Asked Questions

How do I calculate the number of days between two dates?

To calculate days between two dates, select your start date and end date. The calculator computes the exact duration in calendar days, weeks, and months.

Does this date calculator account for leap years?

Yes, leap year extra days (February 29th) are automatically accounted for when calculating dates across years.

How do I add business days to a date?

When adding business days, weekends (Saturday and Sunday) are excluded from the total day count so you get an accurate work-deadline date.

What is a date range calculation useful for?

Date range calculations are used for tracking project milestones, pregnancy timelines, rental agreements, notice periods, and passport/visa duration counts.

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