Greetings

Hæ

“Hæ” (hi) is a common, casual greeting. Saying it twice (“hæ hæ”) is also quite popular, it means the same thing but shows that you are cheerful.

Halló

“Halló” (hello) is used in the same situations as the English “hello”, including when answering the telephone. The double L is pronounced like a normal L since it’s borrowed from a foreign language.^[a]

Góðan daginn

“Góðan daginn” means “Good day to you”. You use this greeting from morning until 6 PM (or 18:00), after that it’s evening and you have to switch to “Good evening to you”. You use this greeting when:

you first meet your family member, friend, or coworker early in the morning
when you meet a stranger on the street (from morning until 6 PM)
when greeting or addressing employees when you’re a client (such as at the store, the café, the bank), including when calling a company on the phone

“Góðan” is the word “góður”, just in a different case. At this point in time you should not think about why this particular phrase uses a different word form,^[b] you should just memorize it as a phrase.

Notes on pronunciation:

The Ð in “góðan” is so soft you can just skip it.
The G in “daginn” makes the sound of J.
The phrase is pronounced [góan dayin].

Sæll

“Sæll” is one of the most common ways to greet someone.^[c] Although it is a relatively formal greeting, it’s used both between good friends and in a professional setting. You should use it when meeting your friend, when writing an email, and when addressing the prime minister. This greeting only works if you’re in a situation where you already know something about the other person, if you don’t know anything about them (such as when greeting a customer, or when writing an email to an organization) you should use “Góðan daginn”.

“Sæll” is an adjective, and therefore it changes its form depending on who it’s describing. If you’re greeting a man you say “Sæll” and if you’re greeting a woman you say “Sæl”. There’s yet another form you need to use when addressing a group of people, but that’s a topic for another time.

Notes on pronunciation:

“Sæll” is pronounced quickly (the æ is short because it’s followed by two consonant letters). The double L is a clicky double L, meaning that you first pronounce a D sound and then a breathy L sound.
The æ in “sæl” is long (it’s only followed by one consonant). Althought the L in “sæl” is a normal L, several sounds lose their voice at the ends of sentences, so “Sæl!” is pronounced with a breathy L.

When to use which greeting

To summarize the above:

If you’re seeing a good friend, use “Hæ” or “Sæll”.
If you’re seeing a good friend early in the morning, use “Góðan daginn”.
If you’re writing an email to someone you know something about, use “Sæll”.
If you’re writing an email to someone you know nothing about, use “Góðan daginn”.
If you’re speaking to a waiter at the coffee shop, use “Góðan daginn”.
If you see a random person on the street, use “Góðan daginn”.
If you see someone you personally know on the street, use “Hæ” or “Sæll”.
If you’re answering the phone, use “Halló”.