All languages, in isolation, are the same difficulty to learn. There are no natural languages that babies can't learn just as well as others. But as adult language learners who already speak at least one other language, certain languages will be easier or harder to learn.
"Easier or harder" isn't exactly the right way to put it. Learning a language is like a marathon — even a marathon on a nice flat track is still a very long distance to run and most people can't do that without training. But some languages have specific features that make them harder (or easier) to pick up, just as certain race courses have different features.
Not only are the race tracks different, but you may or may not have a head start. Imagine running a marathon, but starting halfway down the course — that'd be much easier than doing the whole thing wearing ankle weights. This part of the metaphor represents the languages you already speak. The more similar your native language is to your target language, the more of a head start you have.
One of the hardest parts about learning a language is the sheer number of words you need to know. But English and French share a huge number of very similar words — about 60% of all the words in a contemporary French novel are cognates with English words. In a Japanese text, that number is almost 0%.
We separate languages (roughly) into 4 groups, depending on how different they are from your native language. Since Refold is a primarily English-speaking company, we use English as the native language for these calculations. If you speak a different native language, your version of this chart will look very different. How Long Does It Take to Learn a Language
These are languages that have a common ancestor with English. You have a large head start because you share a lot of vocabulary, grammar features, and sometimes even sounds with your target language.
Many Germanic and Romance languages fall into this category for English speakers:
Most of the 7,000+ languages in the world fall into this category. The marathon track isn't particularly challenging, but you don't start with the big head start of knowing thousands of similar words.
If your target language isn't in the Similar or Distant categories, it's probably here. Some examples:
Some of the biggest languages in the world have both a difficult and complicated race course and features that make them especially hard for English speakers.
Japanese and Korean are notorious for having a fundamentally different sentence structure from European languages. Arabic changes and morphs words in ways that take a long time for English speakers to get used to. Mandarin uses "tones" — just the tone you pronounce a word with can change its meaning from horse to mother.
There aren't many truly distant languages, but the common ones are:
There's also a category even easier than "similar" — cousin languages. These are very closely related languages that share over 50% (often way more) of their vocabulary and have very similar sentence structures and grammar.
For English speakers, this category is essentially empty (Scots and Frisian, basically). But for speakers of other languages, it's very relevant. If you speak Spanish, then Italian, Portuguese, French, and Catalan are all cousin languages. If you speak Russian, then Ukrainian, Polish, Czech, and Slovak are cousins.
Language distance is the biggest factor, but it's not the only one. Your experience matters a lot. If you've already learned two other foreign languages as an adult, you're going to have a much easier time with a third one, even if it's distant. You already understand your personal learning process and have experienced a lot of the pitfalls.
If you have experience with a language related to your target language, that helps enormously. An English speaker who's fluent in Spanish will have a much easier time learning Italian than a monolingual English speaker.
These numbers assume you're using an immersion-based method and are meant as rough planning estimates: Functional Fluency
| Category | Hours to Functional Fluency |
|---|---|
| Cousin language | ~800 |
| Similar language | ~1,350 |
| Other language | ~1,700 |
| Distant language | ~2,700 |
These are based on the Foreign Service Institute's decades of experience, modified to better match the experience of our immersion learning community. For a full breakdown by phase, see the article on how long it takes to learn a language. How Long Does It Take to Learn a Language
Keep in mind that "language distance" isn't meant to be a perfect, objective measurement. All language pairs have their own nuance. But these groupings are useful for planning your learning journey and setting realistic expectations.
The language categories used here are adapted from the Foreign Service Institute (FSI), which groups languages into 4 categories based on how long English-speaking diplomats take to reach professional working proficiency. We've adjusted these categories slightly — adding "cousin languages" (since the FSI doesn't distinguish them separately) and regrouping some languages based on the experience of immersion learners, who have a somewhat different time profile from classroom learners.
The concept of language transfer — that your native language affects how quickly you learn a new one — is well-established in SLA research (Odlin, 1989). Positive transfer (cognates, shared grammar) gives you a head start with similar languages, while negative transfer (false friends, conflicting structures) can slow you down with distant ones. The claim about French-English cognates is supported by corpus linguistics research showing high lexical overlap between the two languages due to their shared history.