Leap Years and Age Calculations

Leap years exist to keep calendar years aligned with Earth’s orbit. For age in years, most software counts full calendar anniversaries, but Feb 29 births need explicit rules in non-leap years.

Common conventions

• Next day: age increments on March 1 in non-leap years.
• Last valid day: increment on February 28.

Legal age for alcohol, voting, or contracts depends on local law — do not infer from a generic calculator.

Explore date deltas with the Age Calculator and Date Difference.