We describe aninsitunondestructive method to measure the intergranular coupling in magnetic thin film recording media based on Stoner–Wohlfarth switching theory [Philos. Trans. Roy. Soc. London A240, 599 (1948)]. The method uses recording write and read heads and a disk test stand to measure a medium’s remanence curves from saturation and demagnetization. Using this technique, we have measured Henkel plots [Phys. Status. Solidi7, 919 (1964)] for single layer and multiple layer longitudinal media, as well as a Henkel plot for a perpendicular thin film with a highly permeable underlayer, which cannot be obtained by the conventional vibrating sample magnetometer method.