This page explains, in plain English, exactly how NameInClass produces the numbers you see on every name profile. Our aim is that anyone could reproduce our figures from the same public data.
UK rankings use the Office for National Statistics (ONS) “Baby names in England and Wales” dataset, which records every first name registered for live births each year from 1996 to 2024. US rankings use the Social Security Administration (SSA) national dataset.
One important detail: the ONS only publishes names given to three or more babies in a year. Names given to one or two children are withheld to protect privacy. This means very rare names may show gaps in some years — that is a feature of the official data, not an omission on our part.
A name’s rank is simply its position when all names of that sex are ordered by the number of babies registered with it in a given year. Rank #1 is the most common. We show the count (how many babies) alongside the rank, because a rank on its own hides how steep the drop-off is — the #1 name is given to thousands of babies, while a name ranked #500 may be given to only a few dozen.
Trend arrows compare a name’s current rank with its rank five years earlier. A large rise or fall (more than five places) is marked with an arrow and the number of places moved; smaller movements are shown as “stable”. Each name profile also charts its full trajectory from 1996 to the latest year.
This is our own calculation. For a class of 30 children, the expected number who share a given name is:
expected = 30 × (babies with the name ÷ total babies registered that year)
Because even the most popular names are given to well under 1% of babies, the expected number in any single class is almost always below one — which is why most names are described as “likely unique” in a classroom. For popular names we express the result as a frequency, for example “around 1 in 3 classes”. It is a statistical estimate for a typical, nationally representative class, not a guarantee for any specific school.
NameInClass holds a profile for tens of thousands of names, but we prioritise names with genuine, recurring usage in the search index. Names that have never reached a meaningful level of use remain available to visitors who look for them directly, but are not submitted for indexing — this keeps the site focused on the names people actually search for.
The ONS releases each year’s baby-name data the following year (2024 data was published in 2025). We refresh our rankings as soon as a new official release is available, and update the “latest data” year across the site at the same time.
Found something that doesn’t match the source data? Please let us know. We verify every report against the original ONS or SSA figures.