Sumimasen and Sumanai: Why Japanese Uses Them to Say Thank You (Compared with Arigatou)

From the verb 済む (sumu) to the meaning of “thank you”: history, logic, and the difference from arigatou

Category: History of Grammar

Why is the word すみません (sumimasen), which is an apologetic expression, also used to express gratitude?

In fact, in Japanese, すみません can mean both “sorry” and “thank you.” In the latter case, however, it is not truly a “thank you”: it expresses an awareness of the inconvenience caused to the other person.

By contrast, ありがとう (arigatou) expresses direct gratitude, without implying any sense of debt or discomfort.

In short:

• すみません = “sorry / thank you (for the trouble)”
• ありがとう = “pure thank you”

In this article, we will look at why these two expressions work in such different ways.

すみません　(sumimasen) - General Overview

In contemporary Japanese, one of the most commonly used and seemingly simple expressions is sumimasen (すみません). It is taught as a way to apologize, but in actual usage it is also very often used to express gratitude. For learners of Japanese, this creates a real interpretive tension: how is it possible that the same expression can mean both “I’m sorry” and “thank you”?

To truly understand this phenomenon, it is not enough to stop at surface usage. It is necessary to go back to the origin of the word, starting from the verb 済む (sumu), and observe how its negative form gave rise to a logic that connects debt, gratitude, and the impossibility of compensating for what one has received.

In this article, a linguistic analysis of sumimasen / sumanai (すまない) will be carried out, tracing its semantic development and clarifying the mechanism that allows the shift from the idea of “not being settled” to that of “being grateful.” The core of this study lies precisely in this point of contact, often overlooked, yet important for understanding Japanese communicative sensitivity.

From here, the comparison with arigatou (ありがとう) will help bring out an essential difference: not two equivalent ways of saying “thank you,” but two radically different perspectives on the relationship between the one who receives and the one who gives.

For a broader analysis of すみません in its classical meaning, that is, as a form of apology, and for a comparison with ごめんなさい・申し訳ありません, this site includes a dedicated article.

The verb 済む (sumu) and its core meaning

To understand the use of すみません as an expression of gratitude, it is helpful to begin with the verb it comes from: 済む (sumu). In Japanese, this verb means “to end,” “to be concluded,” or “to be sufficient.” For example, 事が済む (koto ga sumu) means “the matter is settled / comes to an end.” In contexts involving debt or obligation, it can also mean “to be settled / resolved.” The verb 済む also appears at the end of sentences, often (though not only) connected to a -te form, creating a construction that expresses that something was resolved in a particular way. For example: ちょうど熱が出たから、学校行かなくて済んだ — I had a slight fever, so I ended up not having to go to school (the matter was resolved by not going).

Historically, during the Edo period, 済む was used to indicate that a payment or debt had been settled: once everything had been paid, one could say 済んだ (the past form of 済む, “it is finished / settled”). The opposite—“not being finished / not being settled”—was expressed with the negative form 済まない (sumanai), sometimes shortened in more colloquial speech to すまん (suman). Originally, this expression indicated that something had not been resolved or remained unsettled, such as an unpaid debt. During the Edo period, saying すまない specifically implied “this is not over yet; there is still something left unsettled (between us / toward you)”, often at first in an economic sense, but more generally with the broader idea of an obligation that had not yet been fulfilled.

Over time, すまない developed into an idiomatic expression of apology: if 済む means that “everything is settled,” then saying 済まない (sumanai) implies “this does not settle it / this is not enough.” This idea may refer either to being unable to make up for one’s own mistake or to being unable to repay a kindness one has received. In this sense, すまない (or its polite form すみません) broadly expresses “I cannot simply leave things at this after what I have done / after what I have received,” conveying a feeling of inadequacy or incompleteness toward the other person.

In more colloquial terms, it is somewhat like saying: “I’m sorry — this is not enough.” From a grammatical point of view, すまない is the adjectival negative form of the verb 済む, while すみません is its polite negative form in -masen style. As mentioned above, there is also the variant すまん, a colloquial contraction (often associated with male speech) equivalent to すまない. All of these forms share the same underlying meaning derived from 済む.

The idea of “debt” that connects apology and gratitude

Why does the negative form of 済む lead both to “I’m sorry” and “thank you”? The answer lies in the underlying idea of “not being settled / not being at ease” as long as a debt or obligation toward someone still exists. In other words, すみません conveys a sense of indebtedness or a kind of psychological imbalance toward the other person. This nuance is what connects what at first seem like two opposite interpretations—apology and gratitude. Let us look at both situations:

• In the case of an apology: if I have caused someone trouble or inconvenience, I feel that “things cannot simply end like this”—I owe something in order to make up for it. This is where the expression このままでは済まない comes from—“things cannot be left unresolved like this”—which eventually crystallized into すみません. In practice, it means “I’m sorry; simply apologizing is not enough, and I recognize that I was at fault.”

• In the case of gratitude: if I receive a favor or kindness, in Japanese cultural thinking this is often felt as “having incurred a debt.” A feeling of unease remains until one can return the favor: 借りができて（心が）済まない — “having a debt, the heart cannot feel fully at ease / fully clear.”
  This emotional state of “not feeling settled until one can give something back” is expressed precisely through すみません. In other words, it means: “I am so grateful to you that I feel sorry for having caused you trouble and for not being able to repay you properly.”

In both cases, すみません communicates the idea that “the matter does not end here”: either because an apology is owed, or because a favor is owed in return.

From both an etymological and psychological point of view, apology and gratitude share the same foundation: a feeling of obligation toward the other person. Japanese culture, centered on social harmony (和), places strong emphasis on not causing trouble to others; if that happens, intentionally or not, one feels a sense of responsibility. In the same way, receiving help creates a moral duty to return the kindness, to the point that many people feel uncomfortable if they cannot reciprocate immediately. This is where the habit of expressing gratitude through what is almost a form of apology comes from.

This overlap is something unique to Japanese: in many other languages, “thank you” and “sorry” are clearly distinct, and using them interchangeably would feel confusing. For example, an English speaker might find it strange to hear “I’m sorry” in place of “thank you,” and think: “Why are you apologizing? You didn’t do anything wrong.” And yet, in Japanese, this is completely natural.

In short, すみません is an example of a polysemous ritual expression: since the Edo period, it has been used both to make up for possible offense and to communicate appreciation and recognition in everyday interactions. It is, in that sense, a kind of Japanese “universal formula,” capable of expressing “I’m sorry” and “thank you” at the same time.

Use of すみません (sumimasen) / すまない (sumanai) as expressions of gratitude

In practice, how are these expressions used to say thank you? すみません is the most common polite form: it is often heard in public situations or between strangers, when someone receives a kindness and wants to show gratitude with humility. For example, if someone gives us directions, a Japanese speaker might instinctively respond すみません！, often accompanied by a bow. In this context, すみません is equivalent to “thank you (and sorry for the trouble).”

Likewise, if a store clerk helps us pack a heavy parcel, we might say すみません、助かりました！ — “I’m sorry (for having troubled you), you really helped me,” with the implied meaning “thank you very much, that was a great help to me.”

Japanese speakers understand this nuance very clearly. For example, a cashier might repeat すみません when a customer looks through their wallet for small change after being asked. In reality, the cashier is expressing gratitude for the customer’s cooperation: a genuinely polite form of thanks that acknowledges the small inconvenience caused to the customer. In formal situations, using すみません as a way of thanking someone is often perceived as even more polite than ありがとう, precisely because it shows awareness of the other person’s inconvenience and a humble attitude in receiving the favor.
すまない (plain form) and the shortened variant すまん can also be used to express gratitude, although they appear more often as informal apologies.

It should also be noted that すみません remains a highly versatile expression: besides “sorry / thank you,” it is also used to get someone’s attention (“excuse me” when speaking to a stranger), to introduce a request (“excuse me, could I…?”), and even as a ritual greeting in certain formal exchanges. But focusing specifically on its use as gratitude, the emotional nuance is important: someone saying すみません in response to a kindness is expressing strong gratitude mixed with a sense of guilt for having required effort from the other person. It is a form of thanks with an apologetic attitude—something difficult to translate literally, but essential in Japanese politeness.

Historically, the use of すみません as a form of gratitude is relatively recent (spreading from the modern period onward). Originally, すまない / すみません primarily expressed “this cannot simply be settled like this” in a more general sense.

In texts from the nineteenth century, we can still find すみません used with the literal meaning of “this is not enough as it is / this does not end here.” Only later did the expression enter common usage as a fixed phrase used both for apology and for gratitude.

Differences between すみません and ありがとう when expressing gratitude

Although both can mean “thank you,” すみません and ありがとう convey different nuances. ありがとう (arigatō) is the Japanese word specifically used for “thank you,” without any apologetic connotation. From an etymological point of view, it comes from the archaic adjective ありがたい (arigatai), whose kanji 有り難い literally mean “difficult to exist.” Originally, arigatai referred to something rare and precious, something “out of the ordinary,” and already in the medieval period it came to be used to express appreciation for an exceptional favor.
This relational way of perceiving things is close to what Japanese also expresses through words such as 空気・雰囲気, which reflect the way context influences linguistic behavior.

Saying ありがとう therefore implies “I recognize that what you did for me is not something to be taken for granted; it is precious,” and translates into a feeling of pure gratitude. It is no coincidence that Japanese dictionaries define ありがとう as “a word that expresses a feeling of gratitude.”

すみません, by contrast, while it can certainly be used to say thank you, expresses feelings of apology, regret, or hesitation. When thanking someone with すみません, as we have seen, the speaker places emphasis on their own regret for the trouble caused or on their own inability to fully repay the kindness. In other words, sumimasen emphasizes the dimension of obligation: “I am grateful to you, and I feel sorry that you had to spend time or energy for my sake.” Arigatō, by contrast, emphasizes the dimension of appreciation: “I am happy and sincerely thankful for what you did for me.”

Both expressions acknowledge the kind gesture, but すみません does so in a humble and self-blaming way, while ありがとう does so in a warm and positive way.

Some linguists point out that saying すみません when receiving kindness can risk not openly accepting the goodness of the other person, because one’s own “fault” is brought to the foreground. It is as if the person receiving help automatically places themselves in a position of debt / inferiority, insisting: “sorry for making you go through that trouble.” By contrast, using ありがとう means directly accepting the act of kindness and responding with a positive feeling: “thank you from the heart for what you did.”

For example, if a coworker helps us with some work, saying ありがとう！ (perhaps 「ありがとう、本当に助かったよ」—“thank you, you really helped me”) conveys warmth and explicit gratitude, while すみません、手間をかけて… (“sorry for causing you trouble…”) emphasizes more the discomfort of having needed help. Both responses are polite, but they create slightly different impressions for the person receiving them.

From a cultural point of view, the use of すみません to express gratitude is deeply rooted in traditional Japanese manners, as a sign of humility and consideration toward others. As mentioned above, in many situations it can sound more formal and respectful than a simple ありがとう.

For example, a shop clerk or a stranger helping us might naturally expect a すみません, perhaps even accompanied by ありがとうございます as well.
Using both communicates both “sorry for troubling you” and “thank you very much.”

In recent years, however, there has also been growing reflection on whether ありがとう deserves a more central role: many Japanese people (especially younger speakers) say they prefer receiving a direct thank you, because it feels more positive.

It is also often said that replacing “I’m sorry” with “thank you” can improve relationships and even one’s own sense of well-being: someone who constantly says すみません may begin to see themselves as a “burden on others,” while someone who says ありがとう recognizes help as a form of mutual support, helping create a calmer and more positive atmosphere.

This kind of relational sensitivity, as we already saw in a previous article, is reflected for example in the distinction between 気分・調子・体調・具合, where language tries to capture internal states and perceived conditions.

In short, the difference in meaning between すみません and ありがとう when expressing gratitude lies in the emotional nuance being conveyed: ありがとう expresses pure and direct gratitude, valuing the kind act as something “rare and precious,” without negative implications.

By contrast, すみません expresses gratitude mixed with apology, emphasizing the sense of “debt” and the “trouble” created by the act of kindness.
The choice depends on the context and on the speaker’s intention. Japanese speakers often use すみません out of modesty and respect, especially with strangers or in formal situations, while ありがとう (or more politely ありがとうございます) is used to express genuine and direct appreciation. Understanding this nuance helps reveal the semantic richness of すみません and makes it easier to use it appropriately.

Concluding examples

店員: “袋にお入れしますね” - 客: “すみません、ありがとうございます！”

同僚: “手伝うよ” - あなた: “悪いね、すまん！本当に助かった”

In both cases, すみません / すまん is used to thank someone who has helped us, while also adding the nuance of “sorry for troubling you.” ありがとう (or ありがとうございます in the polite form) remains the standard expression of gratitude in Japanese. Both words, then, mean “thank you,” but they do so with a different emotional center: one directed toward humility and a sense of indebtedness, the other toward joy and the value of what has been received.

Essential bibliography

済む and the concepts of “to bring to completion,” “to settle,” and “to be sufficient.”
(『大辞林 第三版』三省堂；『広辞苑 第七版』岩波書店)

済まない as the negation of that state: something “is not resolved” or “is not settled.”
(『明鏡国語辞典 第二版』大修館書店), (cf. Coulmas 1981; Lebra 1976), (Ide 1989).

ありがとう, derived from 有り難い (“difficult to exist” → rare → precious).
(『広辞苑 第七版』岩波書店)

The difference between ありがとう and すみません reflects two distinct pragmatic perspectives:
appreciation vs. perception of indebtedness.
(Maynard 1997; Lebra 1976)

The concept of relational debt and reciprocity is central in Japanese culture.
(Lebra 1976; 土居健郎 1971)