Small pets can be difficult to weigh. Small mammal such as guinea pigs, hamsters, rats, gerbils, etc. are best weighed on a small postage scale or packing scale. Place a small disposable plastic bowl on the scale and 'zero' the scale. The small pet can then be placed in the bowl and weighed. Be careful not to let your little critter escape or fall. Thoroughly clean or discard the bowl after use. Knowing and tracking your pet's weight is one method used to help determine the overall health of your pet.