The letters g and j are pronounced the same way in some cases and in others they represent different phonemes. Here are some useful rules so you don’t get them wrong anymore!

1. The letter g, before the vowels e and i, is pronounced like the h in hat (but harder), and in this case it coincides with the pronunciation of the letter j:

Agitar (to stir) – engendrar (to cause) – geranio (geranium) – gitano (gypsy)

2. Before the vowels a, o, and u, the letter g sounds like the g in the word get:
Agua (water) – algún (some, any) – gato (cat) – gorra (cap, hood)

3. When you want the e and i to sound like the g in gato, add the letter u; however, the u sound is not uttered:
Aguerrido (hardened, veteran) – conseguir (to manage, to get) – guepardo (cheetah) – guirnalda (garland)

4. When in the combination gu+e/i, the u sound is pronounced, the u has to carry a dieresis (ü).

Paragüero (umbrella stand) – pingüino (penguin)

5. The letter j always has the same sound, a strongly aspired h.
Reloj (clock) – joven (young) – enjabonar (to lather, soap)

6. In some foreign words, both the letter g and the letter j sound like the letter j in the word January.

Adagio – gentleman – jacuzzi – jet set – judo – banjo – gillete – jazz – joule – júnior – disc-jockey – gincana – jeep – jiu-jitsu – majorette

Nos vemos prontito!