Date Calculator
Count days, weeks, months and years between dates
Settings
Date Calculation Results
Time Between Dates Visualization
Complete Guide to Date Calculations
What is a Date Calculator?
A date calculator is an essential tool that helps you determine the exact duration between two dates. Whether you need to calculate project timelines, countdown to special events, or determine age, our calculator provides precise results in multiple units including years, months, weeks, and days.
How to Calculate Date Duration
Our advanced date calculator handles all the complex calculations automatically:
- Enter your start date – The beginning point of your calculation
- Enter your end date – The concluding point of your calculation
- Adjust settings – Exclude weekends or add custom holidays
- Click calculate – Get instant, accurate results
Calendar Awareness
Automatically accounts for varying month lengths and leap years
Multiple Units
Provides results in years, months, weeks, days, and even seconds
Holiday Support
Customize by adding your specific holidays for accurate business day counts
Practical Applications
Date calculations are used in countless real-world scenarios:
Project Management
Calculate project durations and deadlines between start and end dates
Financial Planning
Determine interest periods, loan durations, and investment timelines
Education
Count school days, semester lengths, and academic calendars
Personal Events
Plan weddings, vacations, and countdowns to special occasions
Date Calculation Formulas
While our calculator handles all the math automatically, here’s how date duration is calculated:
Total Days Calculation:
Days = (End Date) – (Start Date)
Returns the difference in milliseconds converted to days
Years and Months Calculation:
Years = End Year – Start Year – (Adjustment if month/day hasn’t occurred)
Accounts for partial years and month overflow
Business Days Calculation:
Business Days = Total Days – Weekends – Holidays
Excludes Saturdays, Sundays, and any custom holidays
Frequently Asked Questions
How do you handle leap years in date calculations?
Our calculator automatically detects leap years (including special century year rules) and adjusts February to 29 days when appropriate. All calculations account for this extra day.
Why are business days important to calculate separately?
Business days (excluding weekends and holidays) are crucial for project planning, service level agreements, and any work-related timelines where non-working days shouldn’t be counted.
Can I calculate dates in the past?
Absolutely! Our calculator works for any dates – past, present, or future. Simply enter your desired start and end dates regardless of their position in time.
How accurate is the months calculation?
Our month calculation is precise, accounting for varying month lengths. If the end date’s day number is less than the start date’s, it counts the full months from the start date’s day.
Interesting Date Facts
The Gregorian calendar has a 400-year cycle with 97 leap years
February is the only month with 28 days (29 in leap years)
The longest possible month has 31 days, spanning 5 weekends