If you’re wondering “how rare is my birthday?”, the answer depends on how many people share your exact birth date compared to others throughout the year.
Use the heatmap or the birthday rarity calculator below to instantly find out where your birthday ranks and how unique it really is.
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How Rare Is Your Birthday?
Discover your rarity score, zodiac sign, personality profile, life path number, and birthday countdown - powered by real U.S. birth frequency data (1994–2014).
Enter Your Full Birthday
All three fields are required to reveal your results
Your Birthday Rank result is ready to share. Challenge your friends to find out how rare their birthday is!
✓ Copied to clipboard!Birth frequency data based on U.S. births from 1994–2014 (CDC NCHS / SSA via FiveThirtyEight). All 366 calendar days ranked by frequency. For informational purposes.
Explore Every Birthday's Rarity
All 366 calendar dates mapped by birth frequency. Click any date to inspect its average daily births and rarity rank.
Birth frequency data based on U.S. births from 1994–2014 (CDC NCHS / SSA via FiveThirtyEight). All 366 calendar days ranked by frequency. For informational purposes.
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Top 10 Most Common vs Rarest Birthdays
Below is the data showing the most common vs. the rarest birthdays based on average daily births:
Most common birthdays
| Rank | Date | Average daily births |
|---|---|---|
| 1st | Sept. 9 | 12.344 |
| 2nd | Sept. 19 | 12.285 |
| 3rd | Sept. 12 | 12.282 |
| 4th | Sept. 17 | 12.201 |
| 5th | Sept. 10 | 12.190 |
| 6th | Sept. 20 | 12.162 |
| 7th | July 7 | 12.147 |
| 8th | Sept. 15 | 12.126 |
| 9th | Sept. 16 | 12.114 |
| 10th | Sept. 18 | 12.112 |
Hence, the above data shows that September is the most common birth month out of all 12 months.
Rarest Birthdays
| Rank | Date | Average daily births |
|---|---|---|
| 366th | Dec. 25 | 6.601 |
| 365th | Jan. 1 | 7.827 |
| 364th | Dec. 24 | 8.103 |
| 363rd | July 4 | 8.825 |
| 362nd | Jan. 2 | 9.356 |
| 361st | Dec. 26 | 9.599 |
| 360th | Nov. 27 | 9.770 |
| 359th | Nov. 23 | 9.919 |
| 358th | Nov. 25 | 10.001 |
| 357th | Oct. 31 | 10.030 |
These aren’t random dips. They happen because:
- Doctors avoid scheduling deliveries on major holidays
- Parents often prefer not to share birthdays with big celebrations
Hence, these dates consistently rank as the most “unique.”
How to Use the Birthday Rarity Calculator?
It is a very powerful tool designed for anyone to use and understand. All you need to do is:
- Enter your correct date of birth
- Click on the “How Rare is My Birthday” button
- Done, you’ll instantly see your results
This tool will perform all the complex calculations in the background and instantly provide you with the results that you can easily understand and share with your loved ones.
Note! This tool will not save any of your data to maintain your privacy. All the calculations will be done in your browser in real time.
How Rare Is My Birthday? A Simple Explanation
When you use our tool, we will analyze several data points and provide you with a comprehensive result:
- Rarity Rank: It is a 1-366 scale, where #1 is the most frequent birthday and #366 is the least frequent.
- Average Births: It is an estimate of how many people, on average, are born on this date.
- Zodiac Alignment: It shows your astrological sign and the core personality traits associated with your sun sign.
Is Leap Day The Rarest?
Mathematically, February 29th is the rarest birth date because it only occurs once every 4 years (to be more precise, 1,461 days), but in reality, it is not.
It ranks 347 out of 366 based on 10.512 average births.
Frequently Asked Questions
1. What is the rarest birthday?
Based on the average daily births, December 25 is the rarest birthday.
2. What is the most common birthday?
In the United States and much of Europe, September 9 is frequently considered the most common birthday. Other dates in mid-September (specifically the 12th and 19th) are also considered fairly common.
3. How is birthday rarity calculated?
Birthday rarity is determined by analyzing national birth registries and census data (such as from the CDC or ONS) over several decades. We look at the average number of births for each specific day of the year and rank them from 1 (the highest frequency) to 366 (the lowest frequency).
4. How rare is my birthday month?
September is the most common birth month, while months like December and February have fewer births. To find out how common your birth month is, simply use our calculator.
Conclusion!
Use our free birthday rarity calculator above to gain fascinating insights into how rare your birthday is.
Whether planning a birthday party, conducting research, or just curious, this tool offers a unique perspective on the day you were born.
Created and reviewed using public birth-frequency datasets.
Last updated: June 2026.
Data Sources & References:
- National Center for Health Statistics (CDC) – Birth Data Trends
- United Nations Statistics Division – Demographic and Social Statistics
I’m the creator of Calculators Ocean, dedicated to building easy-to-use, reliable tools that simplify everyday calculations. Passionate about numbers, logic, and practical problem-solving, I design each calculator to save time and help people make smarter decisions.