This document introduces a method for measuring the equivalent alkane carbon number (EACN) of fragrance oils to rank their polarities. Ranking fragrance polarities allows for more efficient formulation design that is robust across different fragrances. The method involves measuring the salinity at which microemulsion formation occurs for mixtures of each fragrance oil and limonene. From this measurement, the EACN of the mixture and limonene's known EACN, the fragrance's EACN can be calculated. Example EACN values are provided for common fragrance components and solvents to demonstrate the method.