First of all, every state has its own laws defining different classes and misdemeanors, therefore, you should contact your local governing body to verify its state laws. However, the following is a common definition:

A guilty Class 4 felony is usually punishable by an imprisonment of no less than two years and no more than ten years.  and, (subject to subdivision g), a fine of not more than $100,000.

So…to summarize:

Years in prison could range from 2 years to 10 years and the fine could be as much as $100,000.

However, there is some good news about a Class 4 felony.  It is not as severe as the other 3.  A Class 3 could mean 5 – 20 years, a Class 2 could range from 20 years to life in prison and a Class 1 is death or life in prison.