Bachelors degrees in criminology are unusual, and you should keep in mind that these programs probably will not qualify you for a job in the field. Most people who enroll in bachelors degree programs in criminology do so in order to advance their careers in fields like law enforcement, where you often do not need a bachelors degree to qualify for a job.
A masters degree is required for criminologists to work in the field. Keep in mind that some schools call their criminology programs by a different name, such as criminal justice, law and society or crime and justice. You should look into the classes that these programs offer to see if they will prepare you for a job in criminology.
A doctorate in criminology will prepare you for an academic career, where you will be teaching university students and conducting scholarly research. Some schools also offer a combined doctorate in criminology and criminal justice. If you plan to work professionally as a criminologist, you probably do not need to pursue a PhD.