* Level of degree: A PhD will always take longer than a Bachelor's, and a Master's longer than a Bachelor's.
* Specific program requirements: Different universities and even different programs within the same university have varying requirements for credit hours, research projects, thesis/dissertation length, and internships.
* Student's pace: Some students complete their degrees faster than others.
* Field of study: While some fields are *generally* known to have longer programs (like medicine or certain PhDs), there's significant variation within those fields.
Fields like medicine (MD), veterinary medicine (DVM), dentistry, law (JD), and PhD programs in research-intensive areas (e.g., physics, chemistry, some engineering subfields) often take the longest to complete, typically ranging from 7 to 12 years or even longer depending on residency requirements (for medicine, etc.) and the nature of the PhD research.
Therefore, instead of a single "longest" field, we can say that certain fields *tend* to have very long degree programs, but the actual time to completion varies considerably.