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Kaj

#12,943 in 2025Boys' name

Form of Kai

Kaj has been given to 515 babies in the U.S. since 1956. In 2025 it ranked #12,943 of 13,926 boys’ names in use. Its peak year was 2006, with 20 recorded.

Babies named Kaj, 2025

1 in 663,000

Kaj over time, 1880–2025

Boys
0510152018801900192019401960198020002020

Based on births in the U.S. Babies given the name each year. Hover the chart — or focus it and use the arrow keys — for any year. Gaps mean the name was given fewer than 5 times that year; these counts are unpublished.

Kaj: meaning, origin, and history

Form of Kai

Deeper origin not confirmed in the cited records

What Kaj means

Kaj is a form of Kai.

Documented naming usage and pronunciation

Kaj is used in Danish, Swedish, Norwegian and Finnish.

Another recorded pronunciation is /ˈkaj/ for Kaj.

Meaning behind the documented name family

Kaj is a form of Kai. Kai has more than one origin or interpretation.

Origin, language, and formation

Kaj is used in Danish, Norwegian and Swedish.

Related names and everyday forms

Related names include Kai.

Pronunciation and spelling

In Danish, Kaj is pronounced /kajˀ/.

American usage and historical context

In the United States, 515 boys were recorded with the name Kaj between 1956 and 2025. Its highest annual count was 20 in 2006; its best national rank was #3,446 in 1969.

Over 5 years its rank fell, from #9,124 in 2020 to #12,943 in 2025. Over 10 years its rank fell, from #5,866 in 2015 to #12,943 in 2025.

Sources & methodologyReferences, data & attribution

Meaning, origin, and language notes draw on the references below.

American popularity figures use published Social Security Administration records for this exact spelling. Counts below five for a name, sex, and year are omitted.

Wiktionary material is available under CC BY-SA 4.0.

How common is Kaj?

Everything below is computed from the 2025 data — the most recent year available.

Among all babies, 2025
1 in 663,000
5 of 3,315,165 births
Among boys only
1 in 342,000
<0.01% of boys
Rank, 2025
#12,943
of 13,926 boys’ names in use
Coin-flip room size
459,581 kids
Even odds of a second one

Where Kaj sits on the popularity scale

Rarest published (5 a year)#1 — Liam (20,818)

Chance at least one other child shares the name

If the other children were drawn at random from the 2025 national name distribution. Real classrooms cluster by region and community, so treat these as a floor, not a ceiling.

Class of 20Under 1%
Class of 30Under 1%
Grade of 100Under 1%
School of 500Under 1%

Put another way: gather 459,581 children born in 2025 and it's an even bet that one of them is another Kaj. In a class of 30 the chance is Under 1%.

When Kajs were born

Half of everyone ever recorded as Kaj was born before 2005 — so the typical Kaj is around 20 today.

Median birth year
2005
About 20 years old
Biggest decade
2000s
27.2% of all use
Born in the last 25 years
60.4%
A modern name
Recorded since 1950
515
People you could plausibly meet
Choose a decade

2000s — 27.2% of all recorded uses (140).

Is Kaj rising or falling?

Rank movement and count movement can disagree — the number of distinct names in use keeps growing, so a name holding a steady count still slides down the list. Both are shown.

Rank vs 1 year ago
−6,915
Places dropped
Rank vs 5 years ago
−3,819
Places dropped
Rank vs 10 years ago
−7,077
Places dropped
Births vs 10 years ago
0.33×
Fewer babies than then
Share of its own peak
25.0%
Peak was 2006 (20)
Years since peak
19
Years
Year-to-year steadiness
Volatile
38.6% average annual change
Best rank ever
#3,446
1969

Where Kaj is used

Across 1910–2025, Kaj was most concentrated in California — about 1 in — boys, against 1 in 670,489 across all states with data.

00 per 100,000

Most concentrated

  1. 1California1 in —

Shading is the share of that state's recorded boys given this name, not the raw count — otherwise the map would just show which states are biggest. Unshaded states have no published records for this period. U.S. birth records suppress state-year counts below 5; state counts therefore don't add up to the national total. Every state links to its full rankings. Kaj has too little recent state data to map, so this covers all years from 1910.

Kaj around the world

Where Kaj ranks in official birth records elsewhere in the world. Rankings only — the number of births isn’t comparable between places, so it isn’t shown.

  • England & Wales
    1996–2021
    #4,789
    in 2021
  • Ireland
    2023–2023
    #770
    in 2023
  • Norway
    1880–1994
    #553
    in 1994
  • Canada
    2003–2008
    #2,338
    in 2008
  • South Australia
    1973–2013
    #754
    in 2013

Popularity data from Office for National Statistics, Central Statistics Office, Statistics Norway, Statistics Canada and Consumer and Business Services (South Australia). ONS data under Open Government Licence v3.0. CSO, SSB, CBS SA data under CC BY 4.0. StatCan data under Statistics Canada Open Licence.

Kaj by the numbers

The raw record for each sex the name is used for.

As a boy's name

Rank in 2025
#12,943
Trend vs 5 yrs ago
Down 3,819
Best rank ever
#3,446
1969
Peak year
2006
20 that year
First recorded
1956
Last recorded
2025
All-time count
515
Count in 2025
5

Names similar to Kaj

Matched on shared beginnings and endings, similar length, and comparable popularity.

KajuanKajeKajaniKajonKajusKajaiKajaunKajunKajetanKajana

Sibling names for Kaj

Names from the same era and popularity tier — the two things that make a sibling set feel deliberate — skipping lookalike spellings and shared initials.

Explore around Kaj

Top names of 2006, Kaj's peak yearThe 2000s in fullOther names that peaked in 1969Boys' names starting with KShort Danish Boy Names