A fluid permeable heater assembly for aerosol-generating systems includes an electrically conductive flat filament arrangement and a first contact point and a second contact point for electrically contacting the flat filament arrangement. A longitudinal axis is defined between the first contact point and the second contact point. A center resistance Rc is the electrical resistance between two points situated on the longitudinal axis. One of the two points is situated at a distance from the first contact point equal to about 40 percent and the other one of the two points being situated at a distance from the first contact point equal to about 60 percent.