The honest answer is that there is no single magic number. On a busy urban main street, I’d usually start with one bin every 30–50 metres—roughly 100–165 feet—especially near intersections, bus stops, food shops, seating areas, and other places where people pause or generate litter. On quieter stretches, 75–100 metres can be enough. A good rule is that people should never have to walk more than about a minute to find a bin.
But spacing is only half the story. Bins also need to sit where people naturally look for them: at corners, near crossings, beside transit stops, and just before or after food clusters. If a bin is hidden or awkward to reach, people will drop litter nearby even if another bin exists further down the street.
The real test is overflow. If bins are consistently full before collection, the spacing is too wide, the capacity is too small, or pickup frequency is too low. Start with 30–50 metres in high-traffic commercial zones, use 75–100 metres in calmer sections, then adjust based on litter hot spots, event days, tourism, weather, and maintenance schedules. A short pilot period and a few walk-bys will tell you more than a perfect formula.