Critical micelle concentration (CMC) is a key factor in applications of amphiphilic molecules, as it dictates the assembly state of the molecules. Nile Red (NR) is often used as a fluorogenic dye for the measurement of CMC values, but we have observed that NR is prone to aggregation, which leads to reduced reliability in CMC measurements. Here we evaluate 3,3′-dioctadecyloxacarbocyanine perchlorate (DiO) as an alternative fluorogenic dye for the measurement of CMC values. Both NR and DiO provide values comparable to those reported in the literature. However, we demonstrate that DiO provides improved consistency and is more user friendly than NR for measurement of CMC values.