Popular Use Cases
- How many days until your birthday?
- Count business days between two dates (weekdays only)
- Find out if a year is a leap year
- Calculate days between holidays or events
See more in our Date & Time Calculators hub.
Calendar Math
Explore dates, days of the week, and leap years
📅 Day of Week Finder
🗓️ Leap Year Checker
Business Days Calculator
Count the number of business days (weekdays only) between two dates.
📅Formula
Leap Year: Year % 4 = 0 AND (Year % 100 ≠ 0 OR Year % 400 = 0)💡How it works
A leap year occurs every 4 years, except for years divisible by 100 (unless also divisible by 400). This keeps our calendar aligned with Earth's orbit.