The table below lists every month with its day count and any notes worth knowing:
Days in Each Month
| Month | Days | Notes |
|---|---|---|
| January | 31 | |
| February | 28 | 29 in a leap year |
| March | 31 | |
| April | 30 | |
| May | 31 | |
| June | 30 | |
| July | 31 | |
| August | 31 | |
| September | 30 | |
| October | 31 | |
| November | 30 | |
| December | 31 |
The Knuckle Trick
There is a simple mnemonic to memorise which months have 31 days: make a fist and count across your knuckles and the valleys between them, starting from your index-finger knuckle.
- A knuckle (raised) = 31 days
- A valley (between knuckles) = 30 days (or 28/29 for February)
Going left to right: Jan (knuckle) = 31, Feb (valley) = 28/29, Mar (knuckle) = 31, Apr (valley) = 30, May (knuckle) = 31, Jun (valley) = 30, Jul (knuckle) = 31 — then restart from the same index-finger knuckle: Aug (knuckle) = 31, Sep (valley) = 30, Oct (knuckle) = 31, Nov (valley) = 30, Dec (knuckle) = 31.
Because you restart at the same knuckle for August, both July and August land on a knuckle — giving them consecutive 31-day months.
Why Does February Have Fewer Days?
The modern calendar originates from the reforms of Julius Caesar in 46 BC, who introduced the Julian calendar. Before his reform, the Roman calendar was a chaotic 355-day lunar system that required frequent corrections.
Caesar's astronomers aligned the year to the solar cycle of 365.25 days. February had historically been the last month of the Roman year and was used as the "leftover" month — it received whatever days were needed to balance the calendar. When emperors later added days to July (named after Julius Caesar) and August (named after Augustus), February — already the shortest — was left at 28 days.
The leap day (February 29) was added every four years to account for the extra 0.25 days per solar year, a practice refined further by the Gregorian calendar in 1582.
FAQ
Which months have 31 days?
January, March, May, July, August, October, and December all have 31 days — seven months in total.
Which months have 30 days?
April, June, September, and November have 30 days.
How many days does February have?
February has 28 days in a regular year and 29 days in a leap year, which occurs every four years (with rare exceptions for century years).
How can I remember how many days each month has?
Use the knuckle trick: make a fist and count knuckles (31 days) and valleys (30 days or 28/29 for February) from left to right, restarting at the index knuckle after July.