The mass of a rubber band can vary greatly depending on its size and material composition. Generally, a standard-sized rubber band made of natural rubber weighs around 0.1 to 0.2 grams. Larger or thicker rubber bands can weigh more, up to several grams. Rubber bands made from synthetic materials like silicone or latex may have slightly different masses due to variations in density. It's worth noting that these weights are approximate and can vary among different brands and manufacturers.