This research presents a novel reading fluency (rf) measurement formula that accounts for both reading rate and comprehension. Possible formulas were investigated with 68 participants in a strategic reading course in an IEP at a small Pacific Island university. The selected formula's scores demonstrated concurrent validity through strong correlation (r[66] = 0.680, p < 0.001) with the Adaptive Reading Test (ART), an assessment aligned with ACTFL's proficiency levels. Furthermore, when ART scores were regressed onto formula scores, formula scores accounted for 49% of the variance in ART scores (R[superscript 2] = 0.488, F[1, 66] = 62.88, p < 0.001); these results were comparable to a model in which comprehension and rate were the independent variables (R[superscript 2] = 0.514, F[2, 65] = 34.38, p < 0.001). The formula appears preferable to currently available alternatives and ensures that high performance in reading rate cannot compensate for low performance in comprehension nor vice versa. An Excel workbook for exploring formula variants and tracking learners' fluency is provided to readers of Reading in a Foreign Language.