In India, you have two paths to earn a Bachelors degree in Engineering - the most popular one is to complete 12 years of schooling (i.e. high school), and then join a college / university to study Engineering for 4 years. Or, you can complete 10 years of schooling, and then join for a vocational Engineering program in a Polytechnic College. These are usually 3 years program. Once you get a Diploma from the Polytechnic college, you then become eligible to join the usual 4 year Engineering Bachelor programs. But, as you have already completed 3 years of Engineering study in a Polytechnic College, you are allowed lateral entry directly to the second year of the Bachelor Engineering program. This means that under both pathways, you get a degree in the same number of years - 12 years of schooling + 4 years for the Bachelors course = 16 years or 10 years of schooling + 3 years for Diploma Engineering course + 3 years for the Bachelor's course = 16 years. (Note that in both cases, this is in a regular day college, and not a part-time or evening college. Those who have done their 3 years Diploma Engineering courses, but also have to work due to financial constraints have the option to study part-time for a Engineering Bachelor's degree in evening classes too. But these usually are 5 or 6 years program if I remember right).