A rail cant measurement tool and associated methods enable users to measure rail cant. The measurement tool comprises a reference assembly, and a cant angle measurement assembly. The reference assembly comprises a track plane reference bar.The cant angle measurement assembly comprises a web-engaging arm assembly, a spring-biased lock-release mechanism, a rail cant indicator, and a rail cant linear adjustment mechanism. The web-engaging arm assembly comprises pivot arms and web rollers. The pivot arms each comprise upper arm ends and lower arm ends. The upper arm ends are attached to the lock-release mechanism. The reference bar engages opposed rails and the cant angle measurement assembly engages a select rail of the opposed rails. The rail cant indicator indicates rail cant information as determined from the track reference plane and the running surface of the select rail.