Find how many days are in any month of any year — free and instant.
Most months have a fixed number of days — 30 or 31 — but February varies between 28 and 29 depending on whether the year is a leap year. Enter any month and year, and this tells you exactly how many days that month has, correctly accounting for leap years.
This is useful for anything that needs to calculate across month boundaries — billing cycles, loan amortization schedules, or simply double-checking a date calculation by hand.
Worked example: February 2024 shows 29 days, since 2024 is a leap year (divisible by 4, not a skipped century year), while February 2026 shows 28. The same month, two years apart, with a different answer — exactly why "February has 28 days" is only true most of the time, not always.
It checks whether the selected year is a leap year using the same divisible-by-4 (except century years, unless divisible by 400) rule, and returns 29 instead of 28 when it is.
This traces back to the Roman calendar and later adjustments (including changes made under Julius and Augustus Caesar) — the modern pattern is now simply a fixed, memorized convention rather than following any deeper rule.