How Many Languages Should You Learn?

This episode tackles the ongoing debate between learning one language deeply versus learning several at once, and gives a research-backed number for anyone optimizing their study time.

The Real Answer (00:00:12 – 00:02:46)

• There's no universal answer. It depends entirely on what you enjoy and what you want out of language learning.

• The "learn one language deeply" crowd often frames multi-language learners as making a mistake, but there's no reverse pressure on single-language learners to diversify.

• Passion and enjoyment matter more than optimization for most learners.

The Optimized Answer: Interleaving (00:02:46 – 00:06:12)

• Interleaving means studying multiple languages in the same session rather than blocking study by language.

• Research since the 1990s shows interleaving improves retention compared to single-subject study blocks.

• Studies on academic subjects (history, physics, chemistry) show benefits peak around 3 to 5 topics before diminishing returns kick in.

• Related languages (e.g. French and Italian) get extra benefit from shared grammar and vocabulary, pushing the ideal range to 3 to 6 languages.

What Actually Determines Your Number (00:06:12 – 00:08:22)

• Time available per day (fewer minutes = fewer languages you can properly study)

• How related the languages are to each other

• Your prior experience with language learning

• Every language still needs a "critical mass" of daily reviews to make progress

Bottom Line (00:07:28 – end)

• Primary answer: however many languages you want to learn.

• If optimizing for retention: 3 to 6 languages, adjusted for your time and language relatedness.

AI Transcript

00:00:02 All right, and welcome back to another episode of Phrasing FM, a podcast where I talk about languages and my experience building an app to learn them. So today I want to answer the question, how many languages should you learn? It's a bit of a cheeky question with a bit of a cheeky answer, but I do promise I will get to some numbers by the end of this episode, because the real answer to the question is there is no answer. It's however many languages you want.

00:00:32 There seems to be this debate online between whether you should learn a language really deep, or whether you should learn a bunch of different languages. And there's almost a sense of elitism where you need to learn a language really deeply. I oftentimes post online about phrasing and my experience learning a bunch of languages, and I will very often get very snide comments saying that I should try just learning one language, that it's just better to learn one language, that there's no reason to learn multiple languages, that I'm shooting myself in the foot. And I just find this really weird because I don't think there's this sense of elitism on the other side where you see somebody learning one language and it's like, you really should be learning multiple languages. There's this benefit and that benefit and this benefit.

00:01:23 So why are you just learning one language really deeply? It really depends on what you want to do with your language, or even more importantly, what do you enjoy? Do you enjoy studying one language really, really deeply, honing in on your accent and learning the different colloquialisms and regional slang and advanced topics? To me, I don't find that very interesting. I love picking apart different languages, the different connections between them. Are these related? How did this word come to this language? I find that fascinating. I could study that for hours every single day for the rest of my life. Language learning is a passion, a hobby, for me. And yes, I want to improve some languages to get to the point where they're very proficient, but that's not the goal. The goal is to enjoy what you do. So if you want to learn a bunch of languages, just learn a bunch of languages. If you want to learn one language, just learn one language. This is a question nobody else can provide input on into your situation.

00:02:46 But as I promised before, there are some answers to give to this question, specifically when it comes to using phrasing. Phrasing is a language learning app that I built to help myself learn multiple languages, and one of the principles I use in phrasing is a principle I talk about all the time: interleaving. Basically, you study all of your languages at the same time, in the same interface, in the same context, in the same session, and phrasing intelligently prioritizes them, queues them up, and does all the spacing and batching and distribution to optimize this to actually help you learn more languages.

00:03:28 Because there's this concept called interleaving that's been studied and known since the nineties, repeatedly proven that in the same amount of time, in the same amount of study, you can dramatically increase the amount you remember if you just mix things up. If you study multiple topics in the same study session, as opposed to doing all of your French first, then all of your Italian, then all of your German, if you just mix them up, then you're going to remember more.

00:03:59 There have also been studies done into how many different subjects can you mix up. Because if you can mix up two and you do better, if you can mix up three and you do better, at some point there's got to be diminishing returns. This isn't an infinite knowledge hack where you study a hundred subjects at one time and you learn a thousand times more. There's definitely a diminishing return. So where does that return end? The answer seems to be around three to five different subjects. This comes from category induction and memory schemas, and there's been research into how many of these different themes you can study at one time and still get the benefits of interleaving.

00:04:57 Now in these studies, they're looking at history, physics, chemistry, more traditional education topics. When we apply that to language learning, that would be the inter-language categories: French, Spanish, German, going between these different languages and mixing them up.

00:05:13 However, there is additional benefit that can be gained from interleaving when studying inter-language categories. For example, studying present tense, past tense, and future tense in German, or studying the different cases in German. When you interleave those, you'll have an even greater benefit because there is this crossover effect. Interleaving works best with related pieces of material. So I believe when you're learning different languages, the number can be slightly higher. That's why I say three to six, because if you're learning two related languages, there's still this crossover of ideas. For example, if you're learning French and Italian, there's a ton of grammar that's used the same. So when you're studying it in one language, you're getting some benefit in the other language. It almost becomes intra-category information, even if it's inter-language.

00:06:13 So if you really want to maximize the amount of language you get per hour of study, you definitely need to be doing interleaving. You should probably be doing between three and six different languages. That's going to depend on your experience with the languages, how related they are to one another, and how much time you're putting into learning languages. If you're just doing fifteen minutes a day and you try to learn six languages, that's going to slow you down, because at some point you do have to get enough study in a language in a day. You have to reach a critical mass of reviews in a language. That's something I've realized, especially acutely, using phrasing myself.

00:07:06 So how much time are you willing to put in? What do you want to learn, and how related are these languages? What's your familiarity with these different languages, or language learning in general? Take those together, and if you want to learn multiple languages, choose a number somewhere in that range that matches your requirements.

00:07:23 So that would be my official answer for how many languages you should learn. Primary, most important answer: however many you want. Don't listen to people online. I guess that includes me, but listen to me when I say just study whichever languages you want to learn. If this is for a hobby or a passion, just enjoy it, do what makes you happy. And then if you want to really optimize things, don't be worried about going past three, four, five, or even six languages. If some of them are related, that's fine. You're really only going to get some benefit of studying them simultaneously. Keep in mind you will have to do some amount of reviews more if you're studying on the higher number, four, five, or six. You do need to make sure you're at least doing enough work to hit this critical mass of reviews in every single language, but you're going to keep getting benefits out of your review studies as you add numbers up until around here.

00:08:22 One of the coolest parts about building phrasing is as people use it, I can start to do some data science on this and see how much people's languages improve based on how many languages they're studying, how related those languages are, how much cross-pollination of linguistic ideas there is, how much time they're doing in each language per day, and so on. I don't have that information yet, but if you want that information, check out phrasing, go sign up, start learning a bunch of different languages, and you can be included in that data.

00:09:01 So that's the episode for today. Thank you for listening. Have a great day, and I will catch you next time.