Sept Month Number | What Number is September? | DateCal Culator Plus

Sept Month Number: September is the 9th Month

What is the month number for Sept? If you’re filling out forms, coding, or just curious, the answer is simple: Sept (September) is the 9th month of the year. But we’ve built a handy reference tool below so you can check any month’s number instantly.

Whether you need September’s number (9), its season (fall in the Northern Hemisphere), or how many days it has (30), this page has you covered. Use the interactive selector to explore all months.

📅 MONTH NUMBER FINDER

Select any month below to see its number, days, and season.

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September (Sept)

30 days · Fall (Northern) · Spring (Southern)

* Months are numbered 1–12, with January as month 1. “Sept” is a common abbreviation for September.

Why Knowing the Month Number Matters

Month numbers are essential in many contexts:

Forms & documents: Many official forms use numeric dates (MM/DD/YYYY).
Programming: In JavaScript and other languages, months are often zero-indexed (0 = January).
Data analysis: Sorting by month number is easier than by name.
Planning: “Month 9” is quickly understood as September.

Complete Month Number Reference Table

Month	Abbrev.	Number	Days	Season (Northern)
January	Jan	1	31	Winter
February	Feb	2	28/29	Winter
March	Mar	3	31	Spring
April	Apr	4	30	Spring
May	May	5	31	Spring
June	Jun	6	30	Summer
July	Jul	7	31	Summer
August	Aug	8	31	Summer
September	Sep/Sept	9	30	Fall
October	Oct	10	31	Fall
November	Nov	11	30	Fall
December	Dec	12	31	Winter

September: The 9th Month

September’s name comes from the Latin word septem, meaning seven — it was originally the 7th month in the Roman calendar before January and February were added. Today, it’s firmly the 9th month, with 30 days, and marks the beginning of autumn in the Northern Hemisphere and spring in the Southern Hemisphere.

Quick Facts About September (Sept)

Number: 9
Days: 30
Common abbreviations: Sep, Sept
Birthstone: Sapphire
Birth flowers: Aster and Morning Glory
Zodiac signs: Virgo (until Sep 22) and Libra (Sep 23 onward)

Frequently Asked Questions About Sept’s Month Number

What is the month number for Sept?

Sept (September) is the 9th month of the year. In numeric form, it’s represented as 09 or simply 9.

Is Sept the 9th or 10th month?

Sept is the 9th month. October is the 10th, November the 11th, and December the 12th.

Why is September called the 9th month when “sept” means seven?

In the ancient Roman calendar, March was the first month, so September was indeed the 7th month. When January and February were added later, September became the 9th month, but the name stuck.

How many days does September have?

September has 30 days. It’s one of four months with 30 days (April, June, September, November).

What season is September in?

In the Northern Hemisphere, September is in autumn/fall. In the Southern Hemisphere, it’s in spring.

What is September’s number in JavaScript?

In JavaScript, months are zero-indexed, so September is represented as 8 (January = 0, February = 1, … September = 8). But for human-friendly dates, it’s month 9.

Is it “Sep” or “Sept” for September?

Both are common abbreviations. “Sep” is the more modern three-letter form (often used in date formatting), while “Sept” is a traditional abbreviation. Both refer to the 9th month.