Since Korean is an East-Asian language, people tend to associate the difficulty with Chinese or Japanese. But, Korean is much easier to learn than other East-Asian languages. Unlike Chinese, Korean is not a tonal language. This means, that regardless of your accent or pronunciation, one tone equals one meaning.
However, since Korean is the easiest language to read due to its letter-based reading system, that also means Korean is the easiest language to write. You still need to know the grammar, though.
There are no guttural sounds in Korean, like in Arabic or Hebrew. And there are also no consonant clusters, like in Polish or Georgian. But most importantly, Korean is not a tonal language, unlike other East Asian languages. This makes speaking Korean a lot easier.
Riau Indonesian is different from most other languages in how simple it is. There are no endings of any substance, no tones, no articles, and no word order. There is only a little bit of indicating things in time.
Korean is considered to be much easier than Japanese. There are more letters in the Japanese alphabet than in Korean. Japanese also contains more complicated Chinese characters and difficult grammar.
Generally speaking, we might assert that Korean is easier for an English speaker to learn than Mandarin Chinese. But this is very relative. In fact, the US Foreign Service Institute assigns Mandarin Chinese and Korean the same level of difficulty. Both languages are in “Category Four”.
Relatively, Korean would be an easier language to learn. Thanks to its phonetic alphabet and more simplistic grammar rules, Korean is not the most challenging Asian language to learn. Chinese on the other hand is much more widely spoken. This means that finding study materials and practice partners would be easier.
Easiest (about 600 hours of study)
Of these, Spanish and Italian are the easiest for native English speakers to learn, followed by Portuguese and finally French.
Korean is the clear-cut easiest to read and write when compared to Japanese and Chinese, as its alphabet is easier to remember and more logical to Western language speakers.
Korean also only uses one alphabet, which is so much easier than the three alphabets of Japanese or the 10,000+ characters of Mandarin Chinese. The writing system is one of the easiest alphabets in the world to learn, since each individual symbol is made up of different sounds that form one sound together.
If your goal of learning a certain language is related with Japanese culture, then Japanese is the best choice. If your goal is Korean culture such as K-pop, K-drama, or some others, then Korean might be the best choice.
Both analyses demonstrated genetic evidence of the origin of Koreans from the central Asian Mongolians. Further, the Koreans are more closely related to the Japanese and quite distant from the Chinese.
The FSI puts Korean as a Category V language. Which means, it's one of the hardest languages to master. They estimate 2200 hours of study before you can reach fluency in Korean. Or 88 weeks of extremely intense study.
In terms of grammar, Korean is closest to Japanese. It also shares many words of Chinese origin. As such, learning Korean will give you a head start on learning Japanese, as well as some Chinese vocabulary.
Across multiple sources, Mandarin Chinese is the number one language listed as the most challenging to learn. The Defense Language Institute Foreign Language Center puts Mandarin in Category IV, which is the list of the most difficult languages to learn for English speakers.
2. Arabic. Arabic is the queen of poetic languages, the 6th official language of the UN and second on our list of toughest languages to learn.
In the latter half of the 19th century, Ludovik Lazarus Zamenhof had an idea.
Generally, if you're an English speaker with no exposure to other languages, here are some of the most challenging and difficult languages to learn: Mandarin Chinese. Arabic. Vietnamese.
Being trilingual means that you speak three languages with general fluency. Some estimates put the total of the world's trilingual speakers at just over 1 billion people. That's 13% of everyone on Earth!
Unlike other East-Asian languages, Korean isn't a tonal language. This means, that the meaning of the word doesn't change, regardless of what your accent is like. This makes learning Korean much easier than Japanese.
How hard is Korean grammar? The basic rules for grammar are fairly easy, so you should be able to make sentences as soon as you are able to read Hangeul. That means you should be able to make a sentence in the first 2 hours of learning Hangeul. The sentence structure can be as simple as just a single word.
In short, English is an extremely un-Korean and uncomfortable language for Koreans accustomed to two separate varieties of expressions, high and low. It is perhaps for this reason that two Koreans of different social standings could never converse in English even if both are fluent in it.