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How to Calculate Leap Year

What is Leap Year?

A leap year has 366 days — February gets a 29th day. The Gregorian rule corrects for Earth's actual orbital period of 365.2425 days.

Formula

Leap year if: (Year % 4 == 0 AND Year % 100 != 0) OR (Year % 400 == 0) | Adds 1 day to February

Step-by-Step Guide

  1. 1Divisible by 4 → usually a leap year
  2. 2Divisible by 100 → NOT a leap year (century exception)
  3. 3Divisible by 400 → IS a leap year (override century rule)
  4. 42000: yes; 1900: no; 2100: no; 2400: yes

Worked Examples

Input
2024
Result
Divisible by 4; not a century → Leap year ✓
Input
2100
Result
Divisible by 100 but not 400 → NOT a leap year ✗

Frequently Asked Questions

What is Leap Year?

A leap year has 366 days — February gets a 29th day. The Gregorian rule corrects for Earth\

How accurate is the Leap Year calculator?

The calculator uses the standard published formula for leap year. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

What units does the Leap Year calculator use?

Enter values in the units shown in each input field. The calculator displays results in standard units and shows the calculation steps.

What formula does the Leap Year calculator use?

The calculator applies the standard formula for this type of calculation. See the 'How It Works' steps above for the detailed formula breakdown.

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