Kiyaye daidaito yana nufin ƙa'ida ta asali a cikin ilimin kimiyyar lissafi wanda ke bayyana cewa jimillar tsarin rufaffiyar yana dawwama cikin lokaci. Daidaituwa shine ma'auni na daidaitawa ko asymmetry a cikin tsarin jiki, kuma kiyaye daidaito yana nufin cewa daidaito ko asymmetry na tsarin ya kasance baya canzawa yayin aikin jiki. A wasu kalmomi, idan tsarin jiki yana da takamaiman ma'auni ko asymmetry a farkon tsari, zai kiyaye wannan ma'auni ko asymmetry a duk tsawon aikin, kuma yanayin ƙarshe zai kasance daidai da yanayin farko ta fuskar daidaito. Wannan ka'ida tana da mahimman aikace-aikace a cikin nazarin ƙwayoyin subatomic da kuma hulɗar su, da kuma a wasu fannonin kimiyyar lissafi.