¡Hola! I miss you. => Te extraño. I miss you so much. => Te extraño tanto. P.S. to vostok: It is not 'hechar', the right word is 'echar'. => Te echo de menos. It is a common mistake, even native Spanish speakers make it.

Te extraño. Te hecho de menos. Me haces falta.

"Te extraño", "me haces falta",

omg!! so easy n_n Te Extraño (this would be the most common) Te echo de menos (its do used by native spanish speakers although its not very common) both have almost the same meaning

Hi there!!! I miss you= Te extraño :)