We determine fibril stability with an average standard deviation of 3 kJ mol -1 , defining the lower limit of ∆∆G A-U values suitable for analysis. We calculated the corresponding energy perturbations by FoldX, which correlate well with the experimental values (Figure ). To our knowledge, this set of stability measurements represents the largest experimental study to date of amyloid thermodynamic stability of a protein and its mutant variants with a conserved fibril structure as well as the first comparison of experimental and computed thermodynamic stabilities of amyloid fibril variants at such a scale. Our data demonstrates that similar calculations can be used to screen potential variants before labour-intensive production and characterisation of protein sequence variants.