How to Say "I Understand" in Japanese

The most common way is わかりました (wakarimashita), the polite standard used after hearing an explanation or instruction. Japanese also shifts this by politeness level: わかった with friends, かしこまりました in service settings.

The most common way

wakarimashita

I understand / got it — polite and standard, said after hearing an explanation or instruction.

How to say it: Say it with even timing: wa-ka-ri-ma-shi-ta. The 'r' is a single light tap, not an English 'r', and the final 'ta' is crisp.

Other ways to say it

casual
wakatta
Yeah, I get it — casual and direct, used with people you're close to.
When to use it: Say it to a friend, family member or close colleague in everyday conversation.
very polite / service
kashikomarimashita
Certainly / understood — a humble, very polite acknowledgment, standard in customer service.
When to use it: Use it with customers, clients, or anyone you serve in a shop, restaurant or hotel.
business formal
shōchi shimashita
Understood — a formal, businesslike acknowledgment that sounds respectful and professional.
When to use it: Say it to a boss, a client or a superior at work when you accept an instruction.
neutral / colleagues
ryōkai desu
Got it — a neutral, slightly casual 'roger that' common among colleagues.
When to use it: Use it with coworkers or peers in a relaxed workplace, or in work chat.
conversational
naruhodo
I see — a conversational 'that makes sense' that shows you're following, without formally accepting a task.
When to use it: Use it in conversation when someone explains something and you want to show you understand the point.

In a conversation

A
。
Kinyōbi made ni hōkokusho o dashite kudasai.
Please submit the report by Friday.
B
。。
Shōchi shimashita. Kinyōbi desu ne.
Understood. Friday, right?
A
、。
Hai, onegai shimasu.
Yes, please do.

Common mistakes

~~わかります~~ → わかりました
After someone explains something, わかりました means 'I've understood'; わかります sounds like a general 'I understand (in general)' or 'that's understandable'.
~~わかったです~~ → わかりました
わかったです is not natural Japanese; use わかりました for polite speech.
~~了解しました to a customer~~ → かしこまりました
了解しました is fine with colleagues but can sound too casual or blunt to a customer; service staff use かしこまりました.