Street cleanliness in Basel is measured using a cleanliness index from 0 to 5, which is calculated by analyzing video footage from street-sweeping vehicles to detect and classify litter. The Grand Council has set a city-wide target of at least 4.5, meaning streets should be very clean.

In May 2026, the city monitored 4,841 street sections and recorded 122,894 individual measurements. The cleanliness index ranged from a minimum of 3.64 to a maximum of 5.0, with an average of 4.75. Notably, 90.9 percent of measurements were above the required threshold of 4.5, while only 9.1 percent fell below it.

The top five and bottom five streets and districts can be ranked by average cleanliness, but this is only one possible metric. Rankings may shift when using alternative indicators, such as the percentage of measurements that exceed the 4.5 threshold. Tables 1 and 2 below provide full details for both rankings.

Comparing May 2026 to January 2024 shows clear improvement. The percentage of measurements rated as good, meaning 4.0 or higher, rose from 98.8 percent to 99.9 percent. More importantly, the percentage exceeding the required threshold of 4.5 increased from 67.8 percent to 90.9 percent. This indicates that overall street cleanliness in Basel is improving over time. Figure 1 illustrates these trends in a line chart.