감사합니다 vs 고맙습니다: Two Ways to Say Thank You in Korean

Most Korean courses teach 감사합니다 [gamsahamnida] as "thank you" on day one. Then you start watching dramas or walking around Seoul and hear 고맙습니다 [gomapseumnida] just as often, plus shorter versions like 고마워요 and 고마워. Are they interchangeable? Is one more polite? The National Institute of Korean Language (NIKL), which publishes the Standard Korean Dictionary, has answered exactly these questions. Here is what it says.

1. Two different words, one job

The two expressions come from two different adjectives:

The Standard Korean Dictionary defines them like this:

• 고맙다: to feel pleased and glad about a kindness or help someone has given you (남이 베풀어 준 호의나 도움 따위에 대하여 마음이 흐뭇하고 즐겁다).
• 감사하다: to have a grateful feeling (고마운 마음이 있다).

Notice that the definition of 감사하다 uses 고마운, a form of 고맙다. NIKL makes this point in its online Q&A: the two words do not mean exactly the same thing, but their meanings connect, and either one can be used as a greeting of thanks. It adds that because 고맙다 forms the basis of the meaning and is a native Korean word, 고맙습니다 is widely used as the greeting.

2. Is 감사합니다 more polite?

This is the most common belief among learners, and it mixes up two separate things: the word and the speech level.

In another Q&A (August 2026), a senior employee asked whether a new, slightly older colleague saying 고마워요 instead of 감사합니다 was inappropriate. NIKL said that etiquette is not set by the language norms, so it could not give a definite answer, but it pointed out that the difference lies in the ending, not the word:

• 감사합니다 uses the hasipsio-che ending (-ㅂ니다), which shows the highest level of respect to the listener.
• 고마워요 uses the haeyo-che ending (-요), which shows a normal level of respect.

NIKL added for reference: if you want to show high respect, 감사합니다 and 고맙습니다 are both appropriate. In other words, 고맙습니다 sits at the same formal level as 감사합니다. It is 고마워요 that is one step less formal, and 고마워 that is casual.

3. The full ladder

Here is how the forms line up from most formal to most casual. The same ladder works for both words.

Because the ending carries the politeness, you can move either word up or down the ladder. What you should not do is pair a casual ending with someone who expects formal speech.

4. Where each one tends to show up

Since NIKL treats both as correct, the choice is about feel more than rules:

• 고맙습니다 is the native-Korean form, and NIKL notes that it is widely used as a greeting.
• 감사합니다 is equally formal and equally correct, so you never need to avoid it.
• 고마워 is the casual form, so in K-dramas you hear it between friends, siblings, and couples rather than with strangers.

5. A few sentences to practice

• 도와주셔서 고맙습니다. [dowajusyeoseo gomapseumnida] "Thank you for helping me."
• 와 주셔서 감사합니다. [wa jusyeoseo gamsahamnida] "Thank you for coming."
• 선물 고마워! [seonmul gomawo] "Thanks for the present!" (to a friend)

The "-(으)셔서" part means "because you (honored) did," so both formal sentences thank someone for something specific, which sounds warmer than a bare "thank you."

6. Common learner mistakes

1. Using 고마워 with strangers. The word is fine, but the casual ending is not. Step up to 고마워요 or 고맙습니다.
2. Thinking 고맙습니다 is impolite. NIKL says it is appropriate when you want to show high respect.
3. Assuming one word is "more correct." NIKL lists both as usable greetings of thanks; the real choice is the ending.

7. Key takeaways

• 감사합니다 comes from Sino-Korean 감사하다; 고맙습니다 comes from native Korean 고맙다.
• NIKL says the meanings differ slightly but connect, and either can be used to say thank you.
• Politeness comes from the ending: -ㅂ니다 is the highest level, -요 is normal politeness.
• For high respect, NIKL says both 감사합니다 and 고맙습니다 are appropriate.
• 고마워요 and 고마워 are the friendlier and casual steps down.