Ọkọlọtọ gas na-ezo aka na gas nke kwekọrọ na nha nha steeti gas dị mma (PV=nRT) n'okpuru ọnọdụ ọkọlọtọ (nrụgide nkịtị na okpomọkụ, ntụgharị 1 atm na 273.15K). Standard gas bụ okwu na ụlọ ọrụ gas. Standard bekee bụ ụkpụrụ nha nwere otu itinye uche, ezigbo nkwụsi ike na uru ziri ezi. Ha nwere ọrụ ndị bụ isi nke imepụtagharị, ichekwa na ịnyefe ụkpụrụ. A na-eji ha n'ihe gbasara ihe gbasara anụ ahụ, kemịkalụ, biological and engineering iji hazie ngwa nha na usoro nha,