Mass is the weight on an object multiplied by gravity. The Earth's gravity is measured at 9.81m/s squared, while the Moon has no gravity.

To calculate mass you need a balance scale. Put the object on the scale; make sure the scale is turned on and wait for it to settle on a number. The number is the mass of the object. If it's in grams, you can convert it to pounds (1 pound = 453.59237 grams). You can find more information here: http://www.ehow.com/how_2310294_calculat...