Gazovaya postoyannaya universal'naya (molyarnaya) (R) fundamental'naya fizicheskaya konstanta, vhodyashaya v uravnenie sostoyaniya 1 molya ideal'nogo gaza: (sm. Klapeirona uravnenie), gde r - davlenie, v - ob'em molya, T - absolyutnaya temperatura. Gazovaya postoyannaya chislenno ravna rabote rasshireniya 1 molya ideal'nogo gaza pod postoyannym davleniem pri nagrevanii na 1 K. S drugoi storony, Gazovaya postoyannaya - raznost' molyarnyh teploemkostei pri postoyannom davlenii i postoyannom ob'eme: (dlya gazov, blizkih po svoim svoistvam k ideal'nomu). Chislennoe znachenie gazovoi postoyannoi v edinicah SI (na 1984 god): R = 8,31441(26) Dzh/(). V dr. edinicah: erg/() = 1,9872kal/() = 82,057 sm^3 .atm/(mol'^.K). Fizicheskuyu postoyannuyu (gde - molekulyarnaya massa gaza) nazyvayut udel'noi gazovoi postoyannoi.