GOES 1−8 Å peak flux (F_SXR) as function of the mean flare-related changes of the (a) free magnetic energy and (b) total helicity, for 220 flares of sample S​_M1+. The horizontal dashed lines indicate a SXR flux of 5 × 10⁻⁵ W m⁻², i.e., GOES class M5. Numbers in brackets indicate the ratio of confined to eruptive flares within the tested sample. Flares for which a helicity reversal is detected were excluded. Blue and red color indicates confined and eruptive flare type, respectively. X-class and M-class flares are shown as stars and circles, respectively.