A carbon nanofiber-based sensor film is designed and calibrated for force measurement. The sensor is designed for use in structural health monitoring of composite materials. The sensing scheme is based on creating a network of carbon nanofibers on the surface of the composite material. In the experimental scheme a patch of nanofiber reinforced epoxy resin film is developed and adhesively bonded to the laminate. The extension of the sensor film due to the applied force leads to a change in the connectivity of carbon nanofibers in the film, resulting in the change in the resistance of the network. Results show that such sensing schemes have high sensitivity and repeatability. Use of nanofibers can provide a low cost and more efficient alternative to other sensor films that rely on carbon nanotubes.