A speed measurement system for use with a machine having a component rotationally mounted inside a housing may have a first sensing element configured to be mounted to the housing adjacent the component, and a second sensing element configured to be mounted to the housing. The first sensing element may be configured to generate a first signal indicative of a rotational velocity of the component. The second sensing element may be configured to generate a second signal indicative of a rotational rate of the housing. The speed measurement system may also have a controller in communication with the first and second sensing elements. The controller may be configured to determine a rotational speed of the component relative to an offboard reference based on the first and second signals.