MAT 5:41: There are a number of ways in which the distances can be expressed here. Many translations have maintained the literal mile, even in situations where the metric system is employed. “One mile” was presumably the distance a Roman soldier could force a Jew to carry his equipment. What is important here is not the exact distance, but the relation between “one mile” and “two miles.” While this relation will be clear even in settings where miles are unknown, many translations choose to say “one kilometer” and “two kilometers” simply to avoid introducing the unknown word, “mile.”
Actually, it is possible to substitute any distance that takes about 15–20 minutes to walk, or even to express it in walking time; compare the Rincon Zapotec rendering for this verse: “If anyone forces you to carry his load for half an hour, go with this person for a whole hour.” In some cultures it may be natural to express the “mile” in terms of its original meaning in Latin, which is “a thousand paces.”