A 1/8-inch diameter rivet typically weighs around 0.0031 pounds (about 1.4 grams) for a steel rivet of common grip length, according to JiLiang's specifications for 1/8 in. diameter steel rivets. For aluminum alloy rivets with a 1/8-inch diameter and 1/2-inch length, there are roughly 1200 pieces per pound, which means each rivet weighs about 0.00083 pounds or 0.38 grams.

The exact weight depends on the material (steel, aluminum, stainless steel) and the rivet length. For example, aluminum rivets are lighter than steel rivets of the same size. A typical 1/8" steel rivet weighs about 0.0031 pounds, while an aluminum one could weigh a fraction of that.

In summary, a 1/8" rivet weighs roughly between 0.0008 to 0.0031 pounds, depending on material and size specifics.