Variations in the internal moisture content of cotton fibers is a major impediment to the accurate measurement of strength. NIR spectroscopy has been used to generate two types of strength correction factors: additive and multiplicative. Using the NIR spectra for 15 different cottons at 4 humidity levels Partial least squares calibration was used to produce both types of corrections. Additive correction factors were generated by subtracting the strength at 65% RH from the strength measured at the other humidity levels. A ratio of the strength at nonstandard conditions to the strength at 65% RH was also used. PLS was then used to predict these correction factor from the NIR spectra. When the corrections were applied to two different sets of strength measurements standard deviations decreased by a factor of four in both cases.