Date Calculator
Find the exact number of days between two dates, or add and subtract years, months, weeks & days from any date.
Select Date Range
Select two dates
The difference will appear here
Add or Subtract from a Date
Set a date and duration
The resulting date will appear here
How to Use the Date Calculator
Our date calculator makes it easy to find the exact number of days between two dates or calculate a future or past date by adding or subtracting time.
- 1 Days Between Dates: Select a start and end date to get the exact difference in years, months, weeks, days, hours, minutes, and seconds.
- 2 Business Days: Toggle "Exclude Weekends" to count only weekdays (Monday–Friday).
- 3 Add / Subtract: Enter a start date and add or subtract any combination of years, months, weeks, and days to find the resulting date.
Common Uses for a Date Calculator
Business & Contracts
Calculate deadline dates, payment terms (net 30/60/90), and contract expiration dates.
Travel Planning
Find out how many days until your trip, vacation length, or visa expiration dates.
Health & Medical
Track pregnancy due dates, medication schedules, and recovery timelines.
Education
Calculate days until exams, school year length, and assignment deadlines.
History of the Gregorian Calendar
The Gregorian calendar is the most widely used calendar system today. A standard year consists of 365 days, with a leap day added to February every four years (except for century years not divisible by 400).
Introduced by Pope Gregory XIII in 1582, it corrected the Julian calendar's drift of approximately 11 minutes per year. By skipping 10 days (October 4 → October 15, 1582) and refining leap year rules, the Gregorian calendar reduced the error to just 1 day in 3,030 years.
The calendar was adopted gradually worldwide — Catholic Europe by 1582, Great Britain and colonies in 1752, and Greece as late as 1923. Today, it serves as the international standard for civil use.
Frequently Asked Questions
How do I calculate the number of days between two dates?
Enter your start date and end date in the "Days Between Dates" tab. The calculator instantly shows the difference in years, months, weeks, days, hours, minutes, and seconds. You can also toggle "Exclude Weekends" to calculate only business days.
How do I add days to a date?
Switch to the "Add / Subtract" tab. Enter your start date, select Add mode, then enter the number of years, months, weeks, or days. The resulting date is calculated instantly. Use the quick buttons for common periods like +30, +90, or +365 days.
How are business days calculated?
Business days exclude Saturdays and Sundays. Enable the "Exclude Weekends" toggle to count only Monday through Friday. Note: public holidays are not automatically excluded.
Does the calculator account for leap years?
Yes. The calculator automatically handles leap years (years divisible by 4, except century years not divisible by 400). February 29 is correctly included when calculating differences or adding dates across leap years.
What is the difference between calendar days and business days?
Calendar days include every day (Monday through Sunday). Business days include only weekdays (Monday through Friday). For example, a 14-calendar-day period typically contains 10 business days.