How Many Days Are in a Month?
Quick reference for days in each month of the year: 28 or 29 for February, 30 for April, June, Sept, Nov, and 31 for the rest. Average 30.4375 days.
1 month in All Units
Monthly Day Counts & The Gregorian Calendar
In the Gregorian calendar, seven months have 31 days (January, March, May, July, August, October, December), four months have 30 days (April, June, September, November), and February has 28 days in common years and 29 days in leap years.
The mnemonic rhyme "Thirty days hath September, April, June, and November" has served for centuries as a memory aid for calculating month lengths and calendar billing cycles.
Step-by-Step Calculation
- 31 days: January, March, May, July, August, October, December (7 months).
- 30 days: April, June, September, November (4 months).
- 28 days (29 in leap years): February (1 month).
- Average: 365 days ÷ 12 months = 30.417 days (or 30.4375 accounting for leap years).
Frequently Asked Questions
Which months have 30 days?
Four months have 30 days: April, June, September, and November.
Which months have 31 days?
Seven months have 31 days: January, March, May, July, August, October, and December.
What is the average number of days in a month?
Taking leap years into account, the average calendar month is 30.4375 days.