Basel-Stadt is a dynamic urban center whose demographic makeup shapes everything from school planning to pension system sustainability. To understand these pressures, demographers use dependency ratios, which measure the number of people typically outside the workforce relative to those of working age. The youth dependency ratio measures the number of young people (aged 0–19) per 100 working-age persons (aged 20–64). It indicates the relative burden on the economically active population of supporting the younger, non-working generation. A ratio of 0.30, for example, means there are 30 young people for every 100 working-age persons — or roughly 3.3 active persons for every young dependant. The old-age dependency ratio measures the number of people aged 65 and older per 100 working-age persons (aged 20–64). It reflects the pressure on the working population to financially support retirees and is a key indicator of pension system sustainability. A ratio of 0.30, for example, means there are 30 retirees for every 100 working-age persons — or roughly 3.3 active persons supporting each retiree. Looking at the most recent data from 2025 reveals how these two forces currently balance each other in the city.

In 2025, Basel-Stadt had a total population of 210,529 residents. The youth dependency ratio for the total population stood at 27.4, meaning there were roughly 27 young people for every 100 working-age adults, or about 3.6 active persons per young dependant. The old-age dependency ratio was 30.2, indicating about 30 retirees per 100 working-age persons, or roughly 3.3 active persons per retiree. These two ratios are remarkably close, suggesting a balanced demographic structure where the burden of supporting the young and the elderly is nearly equal.

Looking at the longer trend since 1974, the demographic picture has shifted considerably. In 1974, the youth dependency ratio was 35.1, significantly higher than the old-age dependency ratio of 26.8. The youth ratio peaked that year and has since declined, reaching its lowest point of 24.8 in 1990 before rising again to 27.4 in 2025. The old-age dependency ratio followed the opposite trajectory, climbing from its lowest point of 26.8 in 1974 to its highest of 33.9 in 2000 and 2001, before settling at 30.2 in 2025. The year 1979 marks the moment when the old-age dependency ratio overtook the youth dependency ratio, a crossover that has persisted ever since. Over this entire period, the total population evolved from 224,521 in 1974 to 210,529 in 2025, reflecting a modest decline. Figure 1 illustrates the total numbers of young people, working-age adults, and seniors over time, while Figure 3 shows the converging trends of the two dependency ratios since 1974. Figure 2 maps the old-age dependency ratio across Basel's neighborhoods, revealing stark contrasts. The highest ratio was found in Riehen at 48.0, meaning nearly 48 retirees per 100 working-age adults, while the lowest was in Rosental at just 13.7. Notably, the Kleinbasel neighborhoods of Matthäus (20.6), Klybeck (22.3), and Rosental (13.7) had the lowest old-age dependency ratios, and these are also the neighborhoods with the highest concentrations of foreign nationals.

The divergence between Swiss and foreign nationals is even more striking when examining the 2025 data. Among Swiss nationals, the youth dependency ratio was 30.6 and the old-age dependency ratio was 45.7. This means for every 100 working-age Swiss residents, there were roughly 46 retirees, translating to about 2.2 active persons per retiree. For foreign nationals, the picture was dramatically different: a youth dependency ratio of 23.6 and an old-age dependency ratio of just 11.8. This means there were only about 12 retirees per 100 working-age foreign residents, or roughly 8.5 active persons per retiree. Figures 4 and 5, which focus solely on the Swiss fraction of the population, highlight how much higher the old-age burden is among Swiss nationals compared to the total population.

The single most striking insight from this data is that without the younger demographic profile of its foreign residents, Basel-Stadt's old-age dependency ratio would look considerably more challenging. In 2025, the old-age dependency ratio for Swiss nationals alone was 45.7, while for foreign nationals it was just 11.8. The overall ratio of 30.2 is thus substantially lower than it would be if the city's population consisted only of Swiss nationals, underscoring the critical role that foreign residents play in balancing the city's age structure.

Looking ahead, the data suggests that Basel-Stadt's demographic future will depend on whether the current inflow of younger foreign residents continues to offset the aging of the Swiss population, or whether the old-age dependency ratio will resume its upward climb.