If you’re looking at a street bench and wondering whether that metal frame is steel or aluminum, the simplest clue is weight. Aluminum frames feel noticeably lighter, and they usually do not show red rust. Steel frames feel heavier, and if the paint or powder coat gets chipped, you may see reddish-brown rust forming at the scratch.
On cost, steel is generally the cheaper material upfront. Basic mild steel tubing or plate costs less per pound than aluminum, and it is easier to weld using standard equipment. That keeps manufacturing cost lower. The catch is that steel needs a good outdoor finish—paint, powder coating, or galvanizing—so it will not corrode quickly. Once you add a durable coating, steel is still usually the budget option, but the price gap narrows.
Aluminum costs more per pound and often requires more specialized welding or fastening methods, so the initial frame price is usually higher. In many commercial benches, an aluminum frame might run 20% to 50% more than a basic powder-coated steel frame, depending on the design, wall thickness, and finish. The real advantage is that aluminum is lightweight, naturally corrosion-resistant, and easier to handle during shipping and installation. In coastal or rainy environments, it can save you money over time because there is less rust repair and repainting.
So which one is on that bench? If it is a budget-friendly model, heavy, and maybe has a small scratch showing rust, it is probably steel. If it feels light, has no rust after years outdoors, and was priced a bit higher, it is likely aluminum. For most buyers, steel wins on lower initial cost, while aluminum wins on lighter weight and long-term low maintenance.