The number of times a machine multiplies the effort or input force is its mechanical advantage. Mechanical advantage is the ratio of the output force to the input force, so it can be represented through an equation. This equation represents the Actual Mechanical Advantage (AMA) as opposed to the Ideal Mechanical Advantage (IMA). AMA takes into account the amount of the input force used to overcome friction. This equation yields the factor by which the machine changes the input force when the machine is actually used in the real world.
While Actual Mechanical Advantage needs a measurement for the input and output forces, Ideal Mechanical Advantage just needs the input and output distances to fill the formula. The ideal mechanical advantage represents the change in input force that would be achieved by the machine if there were no friction to overcome. It is what is desired of a machine to do. The ideal mechanical advantage is always greater than the actual mechanical advantage because all machines overcome friction while doing work.
A Simple inclined plane example:
For this ramp, the input distance is 12 meters and the output distance is 4 meters. The ideal mechanical advantage of the ramp would be 3. An ideal mechanical advantage of 3 means that the ramp ideally (in the absence of friction) multiplies the input force by a factor of 3.