Interlaboratory comparison study of crack size measurements performed with two different methods

•An interlaboratory study has been conducted to validate and compare crack size measurements performed using two different methods: the 9-Point Average Method and the Area Average Method.•Fifteen laboratories from North America, Europe, and Japan have executed and reported measurements of initial and final crack size on digital pictures of five fracture mechanics specimens of different size and configuration.•Confirming the outcome of a previous investigation by the author, crack sizes measured with the two methodologies have been found in close agreement.•The AA method shows a slightly larger variability than 9PA.•The inclusion of the Area Average Method in all ASTM test methods requiring crack size measurements is therefore recommended.