Is there a way to check the fat% in body accurately, if we are calculating depending on weight, is there a way to check if we are muscular or fatty.

Yes: DEXA scan tells fat percentage and lean mass separately using low dose x-rays ( not for daily use). Hydrostatic weighing is another scientific way to do it. Skin Fold Thickness measurement is a rather easy but less precise way. Bio Electric Impedence. This method is available in consumer weight scales. There are some other scientific ways, all have some limitations.