Days In Month Calculator
Find the number of days in a month for the chosen Gregorian year.
Result for the values shown.
Calculations run in your browser.
What to enter
| Input | Meaning and units |
|---|---|
| Year | integer 1..9999 |
| Month | integer 1..12 |
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 days are in this month and year?
Find the number of days in a month for the chosen Gregorian year.
Common uses
- Find the number of days in a month for the chosen Gregorian year.
How it works
Return Gregorian month length using leap-year rule. 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 Year: 2024; Month: 2. The result is Days: 29.
FAQ
How many days are in this month and year?
Return Gregorian month length using leap-year rule. 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?
Inputs and results must stay within the stated supported ranges.