The second factor to consider is the focal length of the telescope. This is usually measured in millimeters. To make matters more complicated eyepieces also have a focal length. This also plays a major part in figuring the magnification in use at a particular time. This also is measured in millimeters.
Every telescope has a limited range of useful magnifications.
This is where the common bystander or novice observer are usually wrong. The limiting magnification is quite simply based on the size of the objective lens or mirror. As a rule of thumb the average telescope can handle between 50x and 70x per inch of aperture. So for example a small refractor purchased in a department store can really only handle about 100x to 144x magnification. But my telescope says it will work up to 500x.