📅 Date Calculator
Date differences, date math, business days, and more
📅 Days Between Two Dates
➕ Add or Subtract Days
💼 Business Days Calculator
📆 What Day of the Week?
Date Calculator Guide
How to Calculate Days Between Two Dates
To find the number of days between two dates, subtract the earlier date from the later date. Each day equals 86,400 seconds. Our calculator handles leap years, month lengths, and all edge cases automatically.
What Are Business Days?
Business days (also called working days) are Monday through Friday, excluding weekends. Public holidays vary by country and are not automatically excluded — add buffer days for known holidays in your region.
Common Date Calculations
| Calculation | Example | Use Case |
|---|---|---|
| Days between dates | Jan 1 → Dec 31 = 364 days | Project timelines |
| Add days to date | Jan 1 + 90 days = April 1 | Delivery estimates |
| Business days | 5 weeks = 25 business days | Work deadlines |
| Day of week | July 4, 2025 = Friday | Event planning |
| Weeks between dates | 12 weeks = ~3 months | Pregnancy tracking |
Days in Each Month
| Month | Days (Normal) | Days (Leap Year) |
|---|---|---|
| January | 31 | 31 |
| February | 28 | 29 |
| March | 31 | 31 |
| April | 30 | 30 |
| May | 31 | 31 |
| June | 30 | 30 |
| July | 31 | 31 |
| August | 31 | 31 |
| September | 30 | 30 |
| October | 31 | 31 |
| November | 30 | 30 |
| December | 31 | 31 |
Frequently Asked Questions
How many days are in a year?
A regular year has 365 days. A leap year has 366 days, occurring every 4 years (when the year is divisible by 4, except for century years not divisible by 400). The next leap years are 2028, 2032, and 2036.
How do I calculate 30 business days from today?
30 business days = 6 weeks of weekdays. Use the Business Days tab above, enter today as the start date, and count forward. Note this excludes public holidays — add days for any holidays in your region.
What is a Julian date?
A Julian date (or Julian Day Number) is a continuous count of days since January 1, 4713 BC. It's used in astronomy and scientific computing to avoid confusion between calendar systems. It's different from the "Julian calendar."
How many weeks are in a year?
A year has exactly 52 weeks and 1 day (or 2 days in a leap year). This is why the same date shifts by one day of the week each year (e.g., if Jan 1 is Monday this year, it'll be Tuesday next year).
When is the next leap year?
Leap years occur every 4 years: 2024, 2028, 2032, 2036, 2040... The rule: divisible by 4 = leap year, UNLESS it's divisible by 100, UNLESS it's also divisible by 400. So 2000 was a leap year but 1900 was not.
How do I add months to a date?
Adding months can be tricky because months have different lengths. For example, Jan 31 + 1 month = Feb 28 (or 29 in a leap year), not March 3. Our calculator handles this correctly — use the "Add/Subtract Days" tab and select "Months."