Moltes gràcies.

Because moltes has to agree with gràcies.

In Catalan, adjectives and quantifiers agree in gender and number with the noun they modify:

• molt = masculine singular
• molta = feminine singular
• molts = masculine plural
• moltes = feminine plural

Since gràcies is treated as a feminine plural noun, the correct form is moltes gràcies.

Because the expression is historically built on the noun gràcia, and in Catalan the thanking formula became fixed in the plural: gràcies.

So even though in English we just say thanks or thank you, in Catalan the normal expression is plural:

• gràcies = thanks
• moltes gràcies = many thanks / thank you very much

This is just how the expression works; learners should treat gràcies as a fixed polite formula.

It works in both formal and informal situations.

You can say Moltes gràcies:

• to a friend
• to a shop assistant
• in an email
• to a teacher
• in a more formal conversation

It is polite and very natural. It is stronger and warmer than just gràcies, but it is not overly formal.

Yes. Gràcies is extremely common and natural.

The difference is basically one of strength:

• gràcies = thanks / thank you
• moltes gràcies = thank you very much / many thanks

So if you want to sound a bit more appreciative or polite, moltes gràcies is a great choice.

A simple learner-friendly pronunciation is:

MOL-tuhz GRA-see-us

A few useful points:

• moltes has the stress on MOL
• gràcies has the stress on GRÀ
• the gr at the start of gràcies is pronounced together
• the c in gràcies sounds like s before i

Depending on the dialect, the unstressed vowels may sound a little different, but this rough pronunciation will be understood well.

The grave accent in gràcies shows where the stress falls: GRÀ-cies.

Without getting too technical, it tells you that the first syllable is stressed. That is important because stress matters in Catalan pronunciation.

So say:

• GRÀ-cies

not

• gra-CI-es

Yes. Absolutely.

It is very common to use it by itself:

• Someone gives you something → Moltes gràcies.
• Someone helps you → Moltes gràcies.
• Someone answers a question → Moltes gràcies.

You do not need to add anything else unless you want to.

The normal, natural order is Moltes gràcies.

Gràcies moltes is not the standard way to say it. Learners should stick to:

• gràcies
• moltes gràcies

So yes, in practice, the expression is fixed in that order.

Yes. Some very common replies are:

• De res = you’re welcome
• No hi ha de què = don’t mention it
• A tu = thanks to you / same to you

So a very natural mini-dialogue is:

• Moltes gràcies.
• De res.

Only if normal punctuation requires it.

• In running text, you would usually write Moltes gràcies.
• In a message, email ending, or note, you may also see simply Moltes gràcies without a period
• If you want extra warmth or enthusiasm, people may write Moltes gràcies!

So the punctuation changes with context, but the phrase itself stays the same.