This Valentine’s Day, a much larger share of young Americans will be spending the holiday with a partner than those in Italy. According to the international marriage data collected by the United Nations, the average Italian person now gets married at almost 34 years old. In the US, it is just over 28. As a result, over 50% of Americans are married in their early 30s compared to less than 40% of Italians.
The United Nations data shows that typical marriage age varies hugely across the world. Quartz examined marriage ages for countries with at least 5 million people, and for which the United Nations had data for men and women. The very oldest to get married are in Bulgaria at 34, while the youngest are in Niger at almost 21.
What does that average number actually mean? It is not, as you might expect, the expected marriage age for a person born today or the average of all married people, but rather what statisticians call a “singulate mean” (pdf)—a calculation similar to what is used for life expectancy. Basically, the researchers look at the likelihood of people alive today being married at every age from 15 to 54. They then use that to estimate an average for the population at this very moment.
Marriage age is highly correlated with wealth. People in poorer countries like Malawi and Laos tend get married earlier than in richer countries like Norway and Singapore. As a country gets richer, the population tends to starts marrying later. For example, the average marriage age in China rose from just 22 for women and 24 for men in 1990, to 25 and 27 respectively in 2016—a period when the country experienced rapid economic growth.
Not only does the age of marriage tend to get higher with more wealth, the age difference between men and women also declines. The difference in average age of marriage for men and women is less than 2 years in rich countries like Japan, Australia, and the US, but over 6 years in poorer Cameroon and Morocco.
Economics don’t explain everything, though. The Netherlands and Austria have similar GDP per capita, but people in the Netherlands get married about five years later, and the average marriage age for women and men is a year closer. Demographic research suggests that, beyond income, education level and share of people who live in cities are important determinants of marriage age. And some of the difference is a matter of local culture and history, not easily explained by statistics.