Realistically, a standard street bench is built to handle more weight than most people expect. Most municipal or park benches are designed with a static load rating between 500 and 800 pounds, and heavier cast iron or steel models often fall in the 750–1,000 pound range. For two people sitting close together, that usually means a combined weight of 400–600 pounds is completely fine on a well-maintained bench. If you are both around 200–250 pounds, you are well within normal limits.
The key is load distribution. When two people sit close, their weight is not spread across the entire length of the bench, so the center supports and slats do more work. That is why installation matters: a properly anchored bench on a concrete pad will feel solid, while a loose or rusted one may flex or creak even under less weight.
As a general rule, avoid assuming a bench can handle a heavy load if it is damaged, rotted, or not secured to the ground. Static sitting is one thing, but bouncing, standing, or dropping onto the bench adds dynamic force that can easily double the effective load. So if the bench is in decent shape and properly installed, two adults sitting close together are almost always safe. If you are both heavier than average or you notice visible bending, sit slightly apart or choose a bench with center support legs.