a, Here, only the concentration of platelets was changed, all other parameters were kept constant. Interestingly, the iClot predicts the platelet concentration that results in maximum clot contraction. At concentrations above this point, the packing density of platelets drives the final size of the clot rather than the contraction of the scaffold. b, Experimental data (black squares) agree with the iClot predictions that incorporate asynchronous platelet contraction (green), especially when the concentration is above 200 × 106 platelets/mL, whereas the iClot with synchronous platelets (purple) significantly underestimate the clot contraction. Hence, emergent asynchrono-mechanical amplification is concentration dependent and confers an efficiency advantage that is most significant at physiological platelet concentrations.