CrispantCal is a handy tool to quickly calculate volumes for CRISPR-Cas9 based reactions based on the protocol published by Burger et al. (Development 2016).
Simply input once the concentration of your recombinant CRISPR-Cas9 stocks. For each reaction just input the concentration of the guide RNA (sgRNA) and calculations are done automatically, including the amounts of KCl, a component that is critical for a successful reaction.