Archibald Scale

The Archibald Scale (denoted by Ậ) is a measurement of essence bound to and within a person relative to the person's mass. It is named for its inventor, Archibald Rivers. It is primarily used in the Mythiverse, but may be used in other timelines.

Through practice and training, a magic user rated at least 2 Ậ can increase their level, but only by a factor of x0.5x.

The scale
The Archibald Scale is logarithmic, technically ranging from zero to infinity. There are certain ranges established on the scale, marked by distinct differences between users in each range.  * denotes unconfirmed limits.