How do you know if February has 28 or 29 days?

February has 29 days in a leap year and 28 otherwise. A year is a leap year when it is divisible by 4, except for century years (like 1900), which must also be divisible by 400 (so 2000 was a leap year but 1900 was not).

Which months have 31 days?

January, March, May, July, August, October and December have 31 days. April, June, September and November have 30. February has 28 or 29.

Why does the year matter for the number of days?

The year only changes the answer for February, which has 29 days in a leap year and 28 otherwise. Every other month is the same length in every year, so entering the year mainly affects February and the starting and ending weekdays.

How many days are in a year?

A common year has 365 days and a leap year has 366. The extra day is 29 February, added in years divisible by 4 except century years that are not divisible by 400.

How can I remember the month lengths?

The knuckle trick works: count across the knuckles and dips of a fist — knuckles are 31-day months and the dips between them are the shorter months. There is also the rhyme "Thirty days hath September, April, June, and November".

Is anything sent to a server?

No. The calculation runs entirely in your browser and nothing is uploaded.

Days in Month Calculator

How many days are in a month?

Pick a month and year to see exactly how many days it has, whether the year is a leap year, and which weekdays the month begins and ends on. It is handy for planning rotas, payroll periods, rent calculations and anyone who needs a quick, accurate month length.

How it works

The tool asks the calendar for the last day of the chosen month — internally, day 0 of the following month, which is the final day of the month you picked. That value is 28, 29, 30 or 31. It also checks whether the year is a leap year (divisible by 4, except century years which must be divisible by 400) and reports the weekday of the first and last day of the month.

Only February changes length: 29 days in a leap year, 28 otherwise. The other eleven months are fixed.

Example

For February 2024 (a leap year):

Days: 29
First day: Thursday
Last day: Thursday
Leap year: Yes

Month	Days
Jan, Mar, May, Jul, Aug, Oct, Dec	31
Apr, Jun, Sep, Nov	30
Feb (common year)	28
Feb (leap year)	29

Everything is calculated locally in your browser.