Pluto does not have a weight, because weight is a force exerted by one gravitational body on another gravitational body. The dwarf planet Pluto has a mass of 1.31 x 10^22 kilograms, and it's weight would depend on the acceleration at the surface of another planet.
Pluto is less massive than the Earth by a factor of 456. It is so small, in fact, that astronomers reclassified it as a dwarf planet in 2008, because it does not exert enough gravitational force to evacuate small objects from it's orbit. A 100 pound human would weight just 6 pounds on Pluto.