How Many Days Are in Each Month?
Updated September 13, 2026 · 3 min read
Seven months have 31 days, four have 30, and February has 28 — or 29 in a leap year. That is 365 days in a common year and 366 in a leap year.
The full table
| # | Month | Days |
|---|---|---|
| 1 | January | 31 |
| 2 | February | 28 (29 in a leap year) |
| 3 | March | 31 |
| 4 | April | 30 |
| 5 | May | 31 |
| 6 | June | 30 |
| 7 | July | 31 |
| 8 | August | 31 |
| 9 | September | 30 |
| 10 | October | 31 |
| 11 | November | 30 |
| 12 | December | 31 |
July and August are the only two 31-day months in a row, which is the single irregularity that makes the pattern hard to hold in your head.
Two ways to remember it
The knuckle trick. Make a fist and count across your knuckles and the dips between them, starting with January on the first knuckle. Knuckles are the 31-day months, dips are the shorter ones. When you run out of knuckles at July, start again at the first knuckle with August — which is why July and August both land on knuckles, and both have 31 days.
The rhyme. Most English-speaking countries teach a traditional verse beginning "Thirty days hath September" — it dates back to at least the 16th century and lists the four 30-day months, then handles February separately.
Why February is the odd one
The short version: February is what was left over.
The early Roman calendar had ten months and started in March, leaving about 61 days of winter that were not assigned to any month at all. When January and February were eventually added to fill the gap, February landed at the end of the year and got the remainder.
The Romans also preferred odd numbers, considering even ones unlucky — so the months were set at 29 and 31 days wherever possible, and February absorbed the even remainder. Julius Caesar's reform in 46 BC redistributed days to reach 365, pushing most months to 30 or 31, but February stayed short because it was still the month where the leap day would be inserted.
The popular story that Augustus stole a day from February to make August as long as Julius Caesar's July is a much later invention, and there is no Roman source for it.
Which months have 31 days?
January, March, May, July, August, October, December — seven of them, adding up to 217 days, well over half the year.
Which have 30? April, June, September, November — four months, 120 days.
And February? 28 days, or 29 in a leap year. It is the only month short enough to fit exactly four weeks, which is why a 28-day February starts and ends on the same weekday.
Days in a quarter, and in a half
Useful when you are counting towards a deadline rather than a date:
| Period | Days (common year) | Days (leap year) |
|---|---|---|
| Q1 (Jan–Mar) | 90 | 91 |
| Q2 (Apr–Jun) | 91 | 91 |
| Q3 (Jul–Sep) | 92 | 92 |
| Q4 (Oct–Dec) | 92 | 92 |
| First half | 181 | 182 |
| Second half | 184 | 184 |
Q1 is the short one, which is why quarter-on-quarter revenue comparisons usually need normalising.
Counting from here
If you need the date a set number of days out rather than a month boundary, the date calculator handles it — including the awkward case where adding a month to 31 January has to land on 28 or 29 February. And if you are counting down to a specific day, there is a page for every date in the year.
Quick answers
How many days in a year? 365, or 366 in a leap year.
How many days in 3 months? Between 89 and 92, depending on which three. A rough working figure is 91.
Which is the shortest month? February, at 28 or 29 days.
Do any two months always have the same number of days? Yes — in a common year, February's 28 days mean it is the only month that maps cleanly onto four weeks. Every other month is 30 or 31.
Keep reading
- How Many Weeks Are in a Year?
A year has 52 weeks and 1 day — 52 weeks and 2 days in a leap year. Here's the exact figure, why some years have 53 numbered weeks, and what it means for school and work.
- Why Does Easter Change Date Every Year?
Easter moves because it is set by the moon, not the calendar. Here is the rule, the dates from 2026 to 2036, and why Orthodox Easter usually falls later.
- What Is a Leap Year, and When Is the Next One?
Leap years add 29 February to keep the calendar in step with the sun. Here's the rule in full, why 2100 is skipped, and the next leap years in order.