If you're learning Spanish, apart from the fact that pronouncing the "r" sound is already difficult, you may have noticed there are two ways to write it on paper, possibly making matters more difficult. In this post I'll clarify when to pronounce (using IPA transcriptions): /ɾ/ (alveolar flap) and /r/ (alveolar thrill).

rr

Now with the easy one: "rr" is always pronounced /r/, and is always found in the middle of a word. For example

perro - /'pe.ro/

carro - /'ka.ro/

r

"r" can be pronounced either as /r/ or /ɾ/ depending on it's position and what surrounds it.

"r" in the beginning of a word, is always /r/. For example:

rata - /'ra.ta/

río - /'ri.o/

"r" at the end of a word can be either /r/ or /ɾ/, but usually /r/. For example:

cantar - /kan.'tar/ /kan.'taɾ/

jugar - /xu.'gar/ /xu.'gaɾ/

However, if the following word begins with a vowel sound, it becomes necessarily /ɾ/. For example:

amor eterno - /a.'mo.ɾe.'ter.no/

comer higos - /ko.'me.'ɾi.gos/

"r" at the end of a syllable, can be either /r/ or /ɾ/, but usually /ɾ/. For example:

arma - /'ar.ma/ /'aɾ.ma/

eterno - /e.'ter.no/ /e.'teɾ.no/

"r" in any other position inside of a word, is /ɾ/. For example:

brazo - /'bɾa.so/ /'bɾa.θo/

fruta - /'fɾu.ta/

creer - /'cɾe.er/

mirada - /mi.'ɾa.da/

prueba - /'pɾwe.ba/

drama - /'dɾa.ma/

grillo - /'gɾi.ʝo/

EXCEPT when it comes after "l", "n" or "s", OR when "r" comes after the prefix "sub-". For example:

honradez - /on.ra.'des/ /on.ra.'deθ/

alrededor - /al.re.de.'dor/

desregular - /des.re.gu.'lar/

subrayar - /sub.ra.ʝar/

Keep in mind some of these sounds can vary a little in different regions of Spain, Latin America or the Philippines. Hope you find this helpful!