A process for producing ammonia synthesis gas from a hydrocarbon-containing feedstock in a front-end, comprising the steps of steam reforming of said feedstock, obtaining a synthesis gas comprising hydrogen, carbon monoxide and carbon dioxide; a treatment of said synthesis gas including shift of carbon monoxide and subsequent removal of carbon dioxide, wherein the shift of the synthesis gas includes high-temperature shift with an iron-based catalyst and at a temperature greater than 300° C. and the global steam-to-carbon ratio of the front end is 2.6 or less; a corresponding plant and a method for revamping a front-end of an ammonia plant are also disclosed.