Date Difference
Calculate the exact difference between any two dates. Perfect for age calculation, project planning, or countdown to events.
Select Dates
Choose your start and end dates
When does the period begin?
When does the period end?
Date Difference
About Date Difference Calculator
Need to know how many days until your next vacation? Or maybe you're calculating how long you've been at your job? Our date difference calculator gives you the answer in seconds. Just pick two dates and you'll get the difference in days, weeks, months, and even years.
Unlike other calculators, we also show you business days (Monday through Friday) - perfect for work projects, delivery estimates, or any situation where weekends don't count. And yes, we automatically handle leap years and different month lengths.
How It's Calculated
Days Difference = |Date₂ - Date₁| ÷ (1000 × 60 × 60 × 24)
We convert both dates to milliseconds, subtract them, then convert back to days.
Example: From January 1 to December 31 = 364 days (or 365 in a leap year)
Common Date Difference Examples
| From / To | Days | Weeks | Years |
|---|---|---|---|
| Jan 1 → Dec 31 (non-leap) | 364 days | 52 weeks | 1 year |
| Birth → Age 18 | 6,575 days | 939 weeks | 18 years |
| Today → Next Birthday | Varies | ~52 weeks | 1 year |
| Monday → Friday | 5 days | 0.7 weeks | 0.01 years |
Frequently Asked Questions
About the Date Difference
Calculate the exact difference between any two dates. Perfect for age calculation, project planning, or countdown to events.
Formula
Reference Table
| Category | Value |
|---|---|
| Jan 1 to Dec 31 | 364-365 days |
| Birth to 18 years | 6,570 days |