The four rules of thumb for a well-fitting bra

1. The back panel

The back panel should not ride up above the clasps at the front. 

2. The cups

The breasts should fill the cups nicely, with a beautiful, fluent line between cup and breast. 

3. The clasps and the front piece

The clasps and the front piece should be flat against the chest (not against the breasts). 

4. The straps

Straps must not be so tight that they pinch the shoulder or so loose that they fall off the shoulder.