Date & Time Calculators
Calculate days between dates, add or subtract days, and find your exact age.
How Date Calculations Work
Date arithmetic might seem simple, but it's surprisingly tricky. Months have different lengths (28, 29, 30, or 31 days), leap years add an extra day to February every four years (with century exceptions), and daylight saving time can shift clocks forward or backward.
Our calculators handle these edge cases automatically. The Days Between Dates tool counts every calendar day between your two chosen dates and breaks the result down into weeks, months, and years. It also separates weekdays from weekend days — useful for project planning and business day calculations.
Common Uses for Date Calculators
- Project deadlines: Find the date 90 days from contract signing, or count business days until a launch date.
- Pregnancy tracking: Calculate your due date (typically 280 days from the first day of your last period).
- Legal and financial: Determine notice periods, loan maturity dates, or statute of limitations deadlines.
- Travel planning: Count days until your trip or calculate how long your vacation lasts.
- Age verification: Confirm exact age for legal documents, retirement eligibility, or milestone celebrations.
Quick Date Facts
| Period | Days |
|---|---|
| 1 Week | 7 |
| 1 Month (average) | 30.44 |
| 1 Quarter | ~91 |
| 1 Year | 365 |
| 1 Leap Year | 366 |
| 1 Decade | 3,652–3,653 |
Leap Years Explained
A leap year occurs every 4 years to keep our calendar aligned with the Earth's orbit around the Sun (which takes approximately 365.2422 days). The rules are: a year is a leap year if it's divisible by 4, except century years must also be divisible by 400. So 2000 was a leap year, but 1900 was not. The next century leap year will be 2400.