A sensing principle, operating regime, and composition range are identified for force sensing with Galfenol alloys. Magnetization measurements of Fe79.1Ga20.9 and Fe81.6Ga18.4 are performed under applied magnetic field at constant stress. Stress-dependent, linear regions with negligible hysteresis are observed in the Fe79.1Ga20.9 sample over a large range of fields and stresses, for which an analytic model for unbiased loops is formulated. Similar regions are observed in the Fe81.6Ga18.4 sample, with a more limited stress and field range. The small signal operating regime (small in field, not in stress) centered about zero magnetic field is particularly advantageous because in this regime there is no observable hysteresis, since the magnetization process occurs by domain rotation only. The measurements and model show that in this region the susceptibility of Fe79.1Ga20.9 is more sensitive to stress (owing to a significantly lower fourth-order anisotropy constant) with only a small reduction in the saturation magnetization and magnetostriction as compared to Fe81.6Ga18.4. For force sensing, these results suggest the use of Galfenol with an ideal Ga content in the range of 19–22 at. % in which a small, positive fourth-order anisotropy constant is obtained, though in this composition range the magnetostriction is sacrificed.