In 2025, 281 US boys were named Rex, making it the 859th most common boys’ name of the year, down 72 places from #787 in 2024. That is 39 fewer than the 320 boys named Rex in 2024. Its best rank for boys was #170, reached in 1951. That year also had the most boys given the name: 1,503. For comparison, it was #680 in 2015 and #196 in 1950.
Social Security card records list Rex in every one of the 146 years from 1880 to 2025; in 1880 there were 13 babies with the name. In all, 60,590 US babies have been given the name, 0.2% of them girls and 99.7% boys. Its busiest decade was the 1950s, with 13,543 babies named Rex.
Over the 10 years from 2016 to 2025, 3,794 US boys were named Rex; the busiest of those years was 2017, with 434. In 2025 that was about 1 in 6,079 of the boys in SSA’s list for the year.
Among the states, Rex ranked highest in Utah in 2025, at #368 for boys there. It was not in the top 100 of any state. Rarer spellings such as Reaux and Rix are summarised on this page.