Date Calculator

Find the number of days between two dates, add or subtract days/weeks/months from any date, and count business days — all in one tool.

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How the Date Calculator Works

Our date calculator provides two essential functions: finding the number of days between two dates and adding or subtracting a time period from any date. Both modes account for leap years and varying month lengths.

Days Between Two Dates

The calculator computes the absolute difference in calendar days between your start and end dates. It then converts this into weeks, months, and years for easy reference. You'll also see the day of the week for each date, which is helpful for planning events and deadlines.

Business Days vs. Calendar Days

Calendar days include every day — weekdays, weekends, and holidays. Business days count only Monday through Friday. Toggle the "Exclude weekends" option to see just the working days between your chosen dates. Note that public holidays are not excluded by default, as they vary by region.

Add or Subtract Days, Weeks, and Months

Need to know what date is 90 days from now? Or 6 months before a deadline? The Add/Subtract mode lets you pick a start date, enter an amount, and choose days, weeks, months, or years. The result shows the exact date along with the day of the week.

Quick Presets

We include handy preset buttons for common calculations: days until Christmas, days until New Year's Day, and days since January 1st. These set the dates automatically so you can get an instant answer with one click.

Practical Uses

Frequently Asked Questions

How do I calculate the number of days between two dates?
Enter a start date and end date. The calculator subtracts the earlier date from the later one and shows the result in days, weeks, months, and years. It accounts for leap years and varying month lengths.
How are business days calculated?
Business days exclude Saturdays and Sundays. The calculator counts each weekday (Monday–Friday) between your two dates. Toggle the "Exclude weekends" option to see business days vs. total calendar days.
Can I add or subtract months from a date?
Yes. Use the Add/Subtract tab, pick a start date, enter the number of months, and choose add or subtract. If the resulting month has fewer days (e.g., adding 1 month to Jan 31 gives Feb 28), the calculator adjusts to the last valid day.
How do I find how many days until Christmas?
Click the "Days until Christmas" quick preset button. It automatically sets the start date to today and the end date to December 25 of the current year (or next year if Christmas has passed).
Does the calculator account for leap years?
Yes. The calculator correctly handles leap years (years divisible by 4, except centuries not divisible by 400). February 29 is properly counted when it falls within your date range.
What is the difference between calendar days and business days?
Calendar days include every day (weekdays, weekends, and holidays). Business days count only Monday through Friday, excluding weekends. Our calculator shows both counts so you can plan accordingly.

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Methodology, Assumptions, and Limitations

About this page: Date Calculator — Days Between Dates & Add Days is designed to help visitors make faster, better-informed decisions without creating an account or giving up personal data.

This page is designed for fast educational estimates. Results depend on the assumptions and inputs shown on the page and may differ from official statements, provider systems, or professional advice tailored to your situation.

Worked example: Example: run one conservative scenario and one aggressive scenario so you can understand the range of outcomes instead of relying on a single point estimate.

Source References

Editorial Transparency

Last updated: March 9, 2026 · Author: CalcSharp Editorial Team · Reviewed by: CalcSharp Finance Review Desk

CalcSharp publishes free educational calculators and guides. We prioritize plain-English explanations, visible assumptions, and links to primary or official references wherever practical. If you spot an issue, use our corrections process so we can review and update the page.

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