Certain languages are considered relatively easy for English speakers to learn, with the potential to reach reading and speaking proficiency within approximately six months of intensive study. This category includes a combination of Romance and Germanic languages, such as Dutch, Norwegian, French, Spanish, and Italian. However, German and Icelandic need about 9 and 11 months respectively, even though they belong to the Germanic branch of Indo-European family like English. The extended learning duration for these languages can be attributed to their grammar and pronunciation complexities.

There are languages that share only a distant relationship with English, or even none at all. Because of this and various local factors, learning these languages is more difficult for a native English speaker. Some of these may be in a different language family (e.g. Mongolian or Hebrew) but demand roughly the same learning time with the most "difficult" Indo-European languages. A few others though, Arabic, Chinese, Japanese and Korean demand the double effort to reach the same competency level, about 22 months.