Years Between Dates Calculator
Count complete calendar years between dates, with February 29 anniversaries clamped to February 28.
Result for the values shown.
Calculations run in your browser.
What to enter
| Input | Meaning and units |
|---|---|
| Start | Gregorian calendar date in YYYY-MM-DD format; years 0001 through 9999. |
| End | Gregorian calendar date in YYYY-MM-DD format; years 0001 through 9999. |
Understanding your result
Calendar results use the stated counting and anniversary convention. Complete months and years differ from fixed day counts.
Common mistakes
- Counting both end dates when the method excludes a boundary, or assuming all months have equal length.
Check your calculation
- Test a short known interval and a leap-day boundary; for working days, verify your holiday list.
Calculation checks, sources and review limits
How many complete calendar years are between these dates?
Count complete calendar years between dates, with February 29 anniversaries clamped to February 28.
Common uses
- Count complete calendar years between dates, with February 29 anniversaries clamped to February 28.
How it works
y=endYear-startYear; subtract 1 when clamped year anniversary exceeds end. Calendar arithmetic uses the proleptic Gregorian calendar. Explicit calendar dates are independent of local daylight-saving changes. Month/year additions clamp to the last valid day of the destination month. Timestamp arithmetic requires a stated UTC offset and excludes leap seconds.
Worked example
Enter Start: 2020-02-29; End: 2021-02-28. The result is Complete years: 1.
FAQ
How many complete calendar years are between these dates?
y=endYear-startYear; subtract 1 when clamped year anniversary exceeds end. Calendar arithmetic uses the proleptic Gregorian calendar. Explicit calendar dates are independent of local daylight-saving changes. Month/year additions clamp to the last valid day of the destination month. Timestamp arithmetic requires a stated UTC offset and excludes leap seconds.
What assumptions and limits apply?
Feb 29 anniversary clamps to Feb 28. This is not a jurisdiction-specific legal age rule.