*Calculates difference between two dates in years, months, and days.
Date Calculator - Count Days Between Dates
Our free online date difference calculator helps you calculate time between two dates instantly. Perfect for:
- Age calculation - Find exact age in years, months, days
- Project planning - Track durations between milestones
- Event countdowns - Days until weddings, vacations, deadlines
- Financial periods - Interest calculations between dates
This day counter uses precise algorithms to account for leap years and varying month lengths, making it more accurate than manual counting. According to NIST time standards, proper date calculations are essential for legal, financial, and scientific applications.
How We Calculate Date Differences
Our date duration calculator uses a three-step process approved by ISO 8601 standards:
- Year Difference: Counts complete calendar years
- Month Difference: Calculates remaining full months
- Day Difference: Accounts for remaining days
This method ensures accurate results even for:
- Leap years (like 2024, 2028)
- Months with 28-31 days
- Date spans crossing century marks
For scientific applications, see US Naval Observatory date systems.
Practical Uses of Date Calculation
This days between dates calculator helps with real-world situations:
- Employee tenure calculation
- Leave day balances
- Probation periods
- School year planning
- Semester durations
- Assignment deadlines
- Pregnancy due dates
- Vacation planning
- Anniversary tracking
For legal date calculations, refer to CFR date computation rules.
Time Measurement Standards
Our calculator follows international timekeeping standards:
Key facts about date calculations:
- 1 year = 365.2422 days (accounting for leap years)
- Average month = 30.44 days
- 1 week = exactly 7 days
For historical dates, see calendar conversion tools.
More Useful Time Calculators
Explore our full suite of time and date tools:
For world time references, visit Official US Time.