That's an excellent question that doesn't have a single simple answer, as the perfect size depends heavily on several key factors specific to your location. For a typical city block, you're generally looking at a range between 30 and 100 gallons per bin.
The primary consideration is foot traffic. A quiet, residential block might be perfectly served by a couple of 30-40 gallon bins. However, a bustling commercial block with shops, restaurants, and high pedestrian volume will likely need larger, heavy-duty containers in the 60-100 gallon range to prevent overflow between collections.
Collection frequency is the other critical piece. If waste is picked up daily, you can often get away with smaller bins. If collection is only once or twice a week, larger capacity is non-negotiable to avoid litter and pest issues. It's also wise to consider using multiple medium-sized bins rather than one massive one, as this spreads out usage and is easier for sanitation crews to handle.
Ultimately, the best approach is to observe your specific block for a few days. Note how quickly bins fill up and adjust accordingly. Starting with a 50-60 gallon bin is a safe, middle-ground estimate for an average city block, which you can then scale up or down based on real-world need.