New Zealand birthday statistics at a glance
The current New Zealand model places its busiest dates around late August and early September, while the quietest monthly average occurs in December.
Choose a country model
Switching the country updates the summary, daily rankings, monthly averages, and links below.
Country-by-country birthday patterns
This table shows the main endpoints and monthly pattern for all six models. It is the quickest way to see what remains consistent and what changes by country.
| Country | Rarest recurring | Most common | Busiest month | Quietest month |
|---|---|---|---|---|
| United States | January 1 | September 1 | August | December |
| Canada | January 1 | August 31 | August | December |
| United Kingdom | January 1 | August 31 | August | December |
| Australia | January 1 | August 31 | August | December |
| New Zealand | January 1 | September 1 | August | December |
| Ireland | January 1 | August 31 | August | December |
Across the current tables, February 29 is the rarest calendar date, January 1 is the rarest recurring date, August has the highest monthly average, and December has the lowest. The most common exact date is either August 31 or September 1, depending on the selected country.
The rare and common ends of the New Zealand calendar
Birthday patterns by month
The monthly averages show the seasonal neighborhood around a birthday. The exact month and day still determine the main rarity score.
| Month | Average per date | Compared with full-year average |
|---|---|---|
| August | 0.322% | 18.0% above average |
| July | 0.308% | 12.8% above average |
| September | 0.308% | 12.8% above average |
| June | 0.294% | 7.6% above average |
| May | 0.280% | 2.4% above average |
| October | 0.272% | Close to average |
| April | 0.266% | 2.6% below average |
| March | 0.262% | 4.3% below average |
| November | 0.256% | 6.3% below average |
| February | 0.245% | 10.5% below average |
| January | 0.234% | 14.4% below average |
| December | 0.232% | 15.2% below average |
Why an exact date can differ from its month
A busy month can contain a quieter holiday date, and a quieter month can contain dates close to the yearly average. The calculator therefore looks up the exact month-and-day combination first.
The monthly figure is supporting context. It describes the surrounding seasonal pattern without replacing the exact-date rank.
How the rarity rank and score are connected
All 366 dates are sorted from the lowest modeled frequency to the highest. Rank #1 is the rarest position, while rank #366 is the most common.
The calculator converts that rank into a score from 100 at the rare end to 1 at the common end. The percentage, rank, and score are three views of the same underlying table.
Birthday statistics questions
Are these official government birthday statistics?
No. They are modeled daily percentages created for the site's comparison tools.
How many birthday dates are compared?
The model compares 366 possible month-and-day combinations, including February 29.
Why do results change when I switch countries?
Each country loads its own table, including country-specific pattern and fixed-date assumptions.
Does the birth year change the rarity score?
No. The year validates the date and identifies moving holidays. The main score uses the month and day.