What do we use to measure mass? The difference between mass and weight causes a lot of confusion amongst a lot of people. Put simply, weight is a measure of gravity's effect on something. Mass is the amount of matter in an object. Move to a different planet and an object's weight will change, but its mass will be the same. There are a couple of ways to measure mass. The most common method is to use a balance. Hey, wait a minute! (you should be saying) People weigh stuff all the time with a balance!