How accurate are Harvard chance calculators?

I've come across a few websites with Harvard chance calculators. Are they reliable or just gimmicks? I'm looking for some honest feedback. Thanks!

Harvard chance calculators can be useful tools for providing an ballpark estimate of your chances of admission, but they shouldn't be considered as completely accurate or definitive. These calculators often use a combination of factors such as your GPA, test scores, extracurricular activities, and other application details to estimate your probability of admission. However, they usually cannot account for the holistic nature of the admissions process.

Highly selective schools like Harvard consider several qualitative factors that cannot be accurately measured by a calculator. These factors include your essays, letters of recommendation, and the level of challenge in your course selection. Plus, each individual admissions officer brings their own perspective to the evaluation process, which is not something that can be modeled in a calculator.

In short, while Harvard chance calculators can provide a general sense of your admission possibilities, they don't capture the entire picture. It's essential to take their results with a grain of salt and remember that they're just a guide. It's still important to work on submitting the strongest possible application, highlighting your unique qualities, and being prepared for the possibility of a range of outcomes in the admissions process.