How much does the Earth weight?

Earth weighs about 13,170,000,000,000,000,000,000,000 pounds (or 5,974,000,000,000,000,000,000,000 kilograms). Since Earth is too big to be placed on a scale, scientists use mathematics and the laws of gravity to figure out Earth's weight.

weight: 0 (its in space)
mass: 5.972 x 10^24 kg

I'm surprised no one but me saw the problem with those answers, which are correct for the mass of Earth. Weigh assumes a RMS gravity field of one g, big enough to hold all of Earth, which likely exists near most black holes, and stars but perhaps no where else in the Universe, certainly not near Earth. Tide forces would disassemble Earth, if Earth was close enough to Jupiter's strong gravity field.

5.972 x 10^24 kg

It is a relative thing. While we have units of measurement that can be used- they are all arbitrary and dependent on gravitational field or a theoretical constant unit of measurement (molecular weight).
http://www.exploratorium.edu/ronh/weight/ is a little utility to convert earth weight to on other planets.