Here’s the honest answer: for a similar size and style, a recycled plastic outdoor bench typically costs slightly less to moderately less than a true cast-iron bench, and it almost always costs far less to maintain over time.
Basic recycled plastic benches usually sit in the $250–$500 range. A 4-foot recycled plastic garden bench might run $300–$450, while a 6-foot commercial or park-style recycled plastic bench can run $500–$900 depending on the frame, hardware, and whether it is made from solid HDPE lumber.
Cast iron is trickier because the term “cast-iron bench” covers everything from a light imported decorative bench to a heavy ornate antique. Basic cast-iron benches with metal or wood slats often start around $350–$700. True heavy cast iron, ornate backs, or brass and wood accents can push from $800 to $1,500 or more.
So the price comparison often looks like this: entry-level cast iron may be $100–$200 more than a comparable recycled plastic bench. In the mid-range, around $500–$700, the two overlap. At the high end, recycled plastic rarely reaches the price of decorative or custom cast iron.
That upfront comparison only tells half the story. Cast iron is beautiful and strong, but it rusts unless the finish is maintained. In humid, coastal, or rainy climates, you may need to sand, prime, and repaint every year or two. Wood slats may need replacing or sealing. A recycled plastic bench will not rot, splinter, rust, or need painting. Usually soap and water or light pressure washing is enough. That means over a 10-year period, the recycled plastic bench can be significantly cheaper to own, even if the purchase price is close.
If you are buying for a historic garden, formal estate, or you genuinely want the weight and traditional look, cast iron can be worth the extra cost. It has a classic silhouette, feels substantial, and can be restored. Just budget for upkeep or accept the patina.
It can also go the other way. Some budget imported “cast iron look” benches are actually steel or aluminum, and they can be cheaper than recycled plastic. However, they are not usually true heavy cast iron, and they may not last as long.
Bottom line: for most outdoor spaces where low maintenance matters—pools, parks, boardwalks, patios, and commercial seating—recycled plastic is the lower-cost option over time. The pure purchase price is usually lower than true cast iron, and the gap widens when you factor in painting, rust repair, and labor.