All tools / Unit Converter40 miles to km40 miles = 64.37376 kmFormula1 miles = 1.609344 km, so 40 × 1.609344 = 64.37376Need another value? Use the full Unit ConverterOther miles → km conversions1 miles → km2 miles → km3 miles → km4 miles → km5 miles → km6 miles → kmReverse conversion40 km → milesRelated conversions1 km → miles1 cm → inches1 inches → cm1 cm → feet1 feet → cm1 meters → feet