It is obvious that some languages are easier to learn than others, but exactly how hard is it to learn Japanese or Bengali? 

Learning

Well, thanks to the US government agency called  Foreign Service Institute (FSI), which belongs to the US Department of State, we know how long it takes to an English speaker to reach what they call General Professional Proficiency in Speaking (S3) and General Professional Proficiency in Reading (R3). 

The following table has been compiled based on English native speakers of around 40 years old, most of them already knowing at least another language (basically your average CIA agent rather than your average US citizen!)


Category I: Languages closely related to English

23-24 weeks (575-600 class hours)

Afrikaans, Catalan, Danish, Dutch, French, Galician, Italian, Norwegian, Portuguese, Romanian, panish, Swedish

Category II: Languages with significant linguistic and/or cultural differences from English

44 weeks (1100 class hours)

Albanian, Amharic, Armenian, Azerbaijani, Belarusian, Bengali, Bosnian, Bulgarian, Burmese, Cebuano, Croatian, Czech, *Dzongkha, *Estonian, *Finnish, *Georgian, Greek, Gujarati, Hebrew, Hindi, *Hungarian, Icelandic, Ilocano, Irish, Kannada, Kazakh, Kurdish, Kyrgyz, Khmer, Lao, Latvian, Lithuanian, Macedonian, Marathi, *Mongolian, Nepali, Pashto, Persian (Dari, Farsi, Tajik), Polish, Punjabi, Russian, Serbian, Sinhalese, Slovak, Slovenian, Somali, Tagalog, Tamil, Tanchangya, Telugu, Tetum, *Thai, Turkish, Turkmen, Ukrainian, Urdu, Uzbek, *Vietnamese, Xhosa, Zulu

Category III: Languages which are quite difficult for native English speakers

88 weeks (2200 class hours)(about half that time preferably spent studying in-country)

Arabic, Cantonese, *Japanese, Korean, Mandarin, Taiwanese (Hokkien Min Nan), Wu

Other languages: 30-36 weeks (750-900 class hours)

  • German (30 weeks / 750 class hours)
  • Indonesian (36 weeks / 900 class hours)
  • Javanese (36 weeks / 900 class hours)
  • Jumieka (36 weeks / 900 class hours)
  • Malay (36 weeks / 900 class hours)
  • Swahili (36 weeks / 900 class hours)

*Languages preceded by asterisks are typically somewhat more difficult for native English speakers to learn than other languages in the same category.