This article introduces the use of a portable X‐ray fluorescence (XRF) instrument as a non‐destructive tool to rapidly determine fluorochemical concentration on carpet fibers. Most portable XRF instruments are not capable of detecting the primary element in fluorochemicals, fluorine (F) directly. However, fluorochemicals may be combined with chemical taggants, which are measurable. When properly calibrated, the taggant concentrations are a proxy for the F level on carpet fibers, which in turn represents fluorochemical concentration. Results in this research showed that an accuracy of 150 ± 50 ppm of F can be achieved using a portable XRF instrument. This level and accuracy range is specified by manufacturers as an acceptable fluorochemical concentration on carpet fibers. Therefore, a portable XRF instrument can be used in place of the certified chemical burn test, thereby reducing the response time to obtain test results from hours for the chemical burn test to less than 5 min when using the portable XRF technology. This online measurement system for fluorochemical concentration can also be used as a practical means of determining fluorochemical distribution profiles across carpet samples. Copyright © 2013 John Wiley & Sons, Ltd.