Start with the basic street length: one mile is 5,280 feet, or about 1.6 kilometers. Then decide how often you want a public trash can to appear. In a typical low-to-moderate urban area, 500 to 800 feet between cans is common. In a busy commercial district, 200 to 400 feet is more realistic. In very high-traffic areas such as transit stops, tourist zones, and food corridors, 100 to 200 feet may be needed.
The simple base formula is: number of cans = street length ÷ desired spacing. If both sides of the street need cans, double that number. For example, a one-mile street with cans every 400 feet on both sides gives 5,280 ÷ 400 = 13.2, so round up to 14 per side. That is 28 cans. Then add extra cans at intersections, bus stops, subway entrances, parks, schools, benches, and known litter hotspots. A reasonable starting total might be 30 to 35 cans.
Do not rely on spacing alone. Capacity matters. Estimate daily litter volume, check how often collection will happen, and use a safety factor of 1.2 to 1.5. A can that fills up before collection becomes an overflow problem. Also check sidewalk width, accessibility rules, maintenance routes, local codes, and whether cans need liners or locks. Walk the street at different times of day, map foot traffic, and note where litter already accumulates.
For a practical answer, I would calculate a base number by spacing, double it for both sides if needed, add hotspot cans, and then test the result with a short pilot. Install temporary cans, measure fill levels for two to four weeks, and adjust spacing where cans overflow or stay empty. That gives you a defensible number rather than a guess.