The Hebrew phrase “mazal tov” (also spelled mazel tov, or mazel tof) translated means “good luck”. In practice, mazal tov is usually said to mean “Congratulations!”
In modern Israeli pronunciation, it is said with the accent on the second syllable: ma-ZAL tov. In Yiddish and Ashkenazi pronunciation, the accent comes on the first syllable: MA-zel tof.
One can expect to hear people shout “mazal tov” at celebrations like Jewish weddings just after the glass is broken, at brit milah ceremonies, and at bar and bat mitzvahs.
Mazal tov is an appropriate response to any good news, from an engagement to a graduation, a new job, a new house, or any other honour or milestone. In modern Israeli Hebrew, it is common to congratulate people on their birthday using this phrase.
Mazal tov isn’t always a perfect substitute for the English “congratulations”. Some people avoid saying mazal tov to a pregnant woman out of superstition that something might happen to the baby. Instead, it is customary to say “b’sha’ah tovah”, meaning “at a good time”. The implicit wish is that the baby will be born healthy and safe – at which point mazal tov would be an appropriate greeting.
The phrase mazal tov literally means “a good constellation”, implying that the recipient is experiencing good fortune because the stars have aligned for them. In fact, the medieval song incorporating this phrase – “siman tov u’mazal tov”, “a good sign, a good constellation” – makes this even more explicit.
Ancient rabbinic texts speak of good and bad mazalot (constellations), but the phrase mazal tov was not used in a congratulatory manner until the 19th century.
A reasonable literal translation of the phrase might be “good luck” but this doesn’t, as it does in English, carry the connotation of hoping for future fortune.
Rather, it acknowledges present good fortune.
To wish a person future luck in Hebrew, one would say “b’hatzlachah” – “may you have success”.
My Jewish Learning