How do colleges convert CGPA (Indian Marks) to GPA?

I live in India and here in grade 10 we received a CGPA out of 10. I got 9.8.

In 12th grade we get % marks out of 100.

How do they convert our score into GPA?

First, if you're applying to colleges or business schools, don't convert your score. Most colleges have a policy similar to Upenn's:

Students reporting grades from institutions that do not evaluate academic performance on a 4.0 GPA scale should NOT convert their scores to a GPA. Report your scores or grades as your university lists them in your official transcripts, including an explanation of the grading scheme if needed. Keep in mind that we have students from 70 countries in our program and have broad expertise in grading methods around the world.

How does the school do the conversion themselves? One baseline method is to do percentile matching: they look at what percent you are in your graduating class (using data from your school), and then match it to the GPA system in the United States.

The college will then also account for: - International quotas / adjustment -- some schools make the bar higher for international students. - Source school adjustment -- if your incoming school is known to be lax, they'll have a higher bar, and if your incoming school is known to be hard, they'll be easier. (This is also done for domestic applications).