How accurate are body fat calculators, and what can I do to be in the athlete category?

Hello!

I recently came across an online body fat calculator, and I’m wondering how accurate these online tools really are. I input my details, and it gave me a certain percentage, but I’m curious to know if these are reliable or if there's a better way to track body fat more accurately.

I have an active lifestyle and am working on getting into the athlete category for body fat percentage. For context, I’m in my early 20s and aiming for a healthier and more toned physique. What’s the ideal body fat percentage for Indian women in their early 20s, and what can I do to reach this goal? Any tips on workouts, nutrition, or lifestyle changes would be really helpful!

Thanks!