Many studies addressing the toxicity of silver nanomaterials have found that smaller sized silver nanoparticles are usually more toxic to organisms and in cell culture than particles of larger sizes yet it is not entirely clear why. We investigated the size dependent toxicity of silver nanoparticles by measuring the response of embryonic zebrafish (Danio rerio) following exposure to a library of thirteen distinct silver nanoparticle size distributions with mean diameters between 8.9 nm and 112.6 nm. Data analysis using dose‐response modeling revealed that silver nanoparticles (AgNP) induced embryo toxicity that is dependent on the total surface area and not on the mass or particle number in solution. Included in this study is a comparison between embryo toxicity induced by silver nitrate (AgNO₃) and AgNPs for cardiovascular endpoints, as well as an investigation into the influence of the chorion on AgNP toxicity. This study demonstrates the importance of using alternative dose metrics in nanotoxicology, and highlights the value of using the embryonic zebrafish to explore nanomaterial structure activity relationships.