Honestly, two people can handle most concrete outdoor benches, but “manage” depends on the specific bench and your route. A small to mid-size concrete bench, roughly 4 to 5 feet long, typically weighs between 180 and 350 pounds. That is heavy, but not impossible for two adults, especially if you use a dolly, furniture straps, or a hand truck. If you are looking at a larger commercial-style bench with a thick seat and full back, it can easily hit 400 to 600 pounds or more. At that weight, two people might still move it on flat ground with the right equipment, but stairs, slopes, or tight corners can make it dangerous, and a third person or lift-gate delivery is worth it.
The tricky part is not just the weight; it is the shape. Concrete benches are dense, low to the ground, and have no comfortable handles. The safest method is to keep the bench upright on a heavy-duty furniture dolly, strap it down, and roll it. If you need to cross grass or gravel, lay down plywood or use a dolly with large pneumatic wheels. For a short move across a flat patio, two people can tilt and walk it, but lift with your legs and keep your back straight.
When it comes to actual installation, the bench itself does most of the work. Set it on a firm, level surface such as compacted gravel, paver base, or an existing concrete patio. Check level from front to back and side to side. Most residential concrete benches do not need anchoring because their weight keeps them in place. If you live in a high-wind area or want extra security, a few small dabs of exterior construction adhesive or setting the legs into a shallow paver base works fine.
So yes, if you are reasonably fit, have a dolly and a clear path, two people can install a concrete outdoor bench. Just do not try to dead-lift a 400-pound bench out of a truck bed without equipment. If the bench is over 350 to 400 pounds or your path includes stairs, hire extra hands or choose delivery with lift-gate service.