Honestly? It depends on the bench and where it ships from, but most street benches land somewhere between “open the crate and sit” and “clear your entire Saturday.
If you order a commercial-grade bench from a site that specializes in park or streetscape furniture, many models ship partially assembled. The heavy cast iron or steel frame usually comes in two end pieces, and the wood or metal slats come separately. That means you will need some basic tools—typically a socket wrench, an adjustable wrench, and maybe an Allen key. You are not rebuilding an engine, but you are attaching maybe 8 to 16 bolts. Give yourself 45 minutes to two hours, not a full weekend.
There are pre-assembled options. Some manufacturers offer “fully assembled” or “knocked down” choices. Fully assembled benches arrive ready to place, but they cost more to ship because they take up more room on a truck and often require a pallet jack or two people to move. If you choose that route, the only tool you might need is a knife to cut the packaging.
The real answer: check the product listing before you click buy. Look for words like “ships fully assembled,” “some assembly required,” or “KD” (knocked down). If it says KD, plan for a socket set and a level. If it says fully assembled, plan for pizza and someone strong to help you lift it.
One pro tip: even if assembly is simple, use a level and do not fully tighten every bolt until the bench is sitting flat on the ground. That prevents that annoying wobble later.
So no, you probably do not need a weekend—just a wrench, a little patience, and maybe a cold drink afterward.