The　scratch　test　is　used　for　quality　control　mostly　in　phenomenological　ways,　and　whether　fracture　toughness　can　be　obtained　from　this　test　is　still　a　matter　of　debate　requiring　further　elucidation.　In　this　paper,　values　of　the　fracture　toughness　of　copper　obtained　by　different　scratch-based　approaches　are　compared　in　order　to　examine　the　applicability　of　scratch-based　methodologies　to　characterize　the　fracture　toughness　of　soft　metals.　The　scratch　response　of　copper　to　a　Rockwell　C　diamond　indenter　is　studied　under　a　constant　normal　load　condition.　The　variations　of　penetration　depth,　residual　depth,　and　residual　scratch　width　with　applied　normal　load　are　quantified　from　spherical　to　sphero-conical　contact　regimes　by　piecewise　functions.　A　newly　proposed　size　effect　law　is　found　to　be　the　most　suitable　for　scratch-based　approaches　to　characterizing　the　fracture　toughness　of　soft　metallic　materials　with　significant　plasticity.　A　simple　expression　relating　the　nominal　stress　to　the　penetration　depth　is　proposed　for　the　spherical　contact　regime　and　gives　almost　the　same　value　of　fracture　toughness.　The　residual　scratch　width　provides　useful　information　on　pile-up　of　material　and　on　the　spherical　tip　radius　of　the　indenter.　It　is　found　that　the　values　of　the　fracture　toughness　obtained　from　the　microscratch　test　are　influenced　by　the　data　range　for　analysis.　©　2021　Author(s).