Calculation Result
Calculation History
Formula Used
Calendar years use complete anniversaries plus remaining months and days. Decimal methods divide elapsed days by the selected year basis. Financial conventions may produce different values for identical dates.
Decimal years = elapsed days ÷ selected days per year Actual/Actual years = sum of each partial-year fraction using 365 or 366 days 30/360 years = convention-adjusted days ÷ 360How to Use This Calculator
- Select the calculation mode that matches your task.
- Enter the required dates, years, or time value.
- Choose a day-count basis and rounding method.
- Adjust inclusion, fiscal, academic, or leap-day settings.
- Select Calculate to view detailed results and steps.
- Copy, share, print, or export the result when needed.
Example Data
| Mode | Input | Typical result | Useful setting |
|---|---|---|---|
| Years between dates | 2020-01-01 to 2025-01-01 | 5 complete years | Actual/Actual |
| Add years | 2024-02-29 plus 1 year | 2025-02-28 | February 28 rule |
| Age | Birth date to selected date | Years, months, days | Anniversary countdown |
| Convert days | 365.2425 days | 1 average year | Average Gregorian |
| Compare ranges | Two project periods | Longer range and difference | Same basis for both |
Frequently Asked Questions
What is a completed year?
A completed year ends on an anniversary date. Incomplete months and days are shown separately. This avoids overstating a person’s age or measured period.
Why do decimal-year results differ?
Different methods use different year lengths. Leap years also change actual elapsed fractions. Select the convention required by your application or contract.
How is February 29 handled?
The calculator supports February 28 or March 1. This matters when adding whole years. Choose the rule required by your institution or agreement.
What does Actual/Actual mean?
Actual/Actual uses real elapsed days. Each year uses its actual length. Leap years therefore use exactly 366 calendar days here.
What is the 30/360 method?
It treats months as thirty days. A year therefore contains 360 days. Financial contracts commonly specify the exact variation being applied.
Can I include both dates?
Yes, enable both inclusion options. The calculator then counts both boundary dates. This setting is useful for occupancy and service periods.
Are fiscal years calculated separately?
The result identifies fiscal periods touched. Choose the fiscal starting month first. Exact fiscal rules may vary between organizations and jurisdictions.
Does time zone affect date-only results?
Date-only calculations use fixed calendar dates. Time zones matter when times are included. Use consistent settings for both endpoints and every comparison.
Can this replace professional advice?
No, it provides mathematical date calculations. Legal and financial definitions may differ. Verify important decisions with appropriately qualified independent professional advisers.