Fudged population

A fudged population is a city that uses a different formula to calculate its population. This can only be applied to a charter city, and has to be approved by an administrator before use.

Realism
The most common purpose for fudged populations are realism. Cities with over 250k population in Cities: Skylines are often much larger in real life and therefore adding a fudged population adds more realism to the city.

The most notable example is St. Matthew's, the largest city in the Cities Union. Even without a fudged population, the city would still be the most populous in the union, so the fudged population makes the city's large size be more reasonable

Formula
The current formula for the Cities Union is x·5=f, where x would represent the city's unfudged population and f would represent the fudged population. Simply put, you would multiply a city's population by five and the answer would be the city's fudged population