Full disclosure: My editor asked me to answer this question—“What’s the fastest language in the world?”—because I like writing about both language and strange, global superlatives. Pretty quickly I realized that there’s a basic problem (albeit a fun one!) with the question: We first have to determine what we even mean by “fastest.” Does that mean the number of words or syllables spoken in a set amount of time? The amount of information conveyed? The language with the fewest words or syllables to convey a set statement? The language that can be understood when cranked up to the highest speed? What even is English jacked up to 4x? 10x?

Francois Pellegrino is mostly a quantitative linguist, meaning his work often includes measuring differences among languages and hunting for explanations behind those differences. He’s worked on language speed a few times, including on one study that compared 17 different languages in a variety of metrics.

Pellegrino prefers looking at syllables rather than individual sounds (phonemes, to linguists) or words. “So the sounds per syllable, you have two ways to look at it,” he says. “You have one way, which is to look at how fast they are produced and what kind of information they convey. But you can also basically ask people to listen to unknown languages and ask them whether it sounds fast or not. So you have the perceptual aspects, and the articulatory and production aspects.”

Both speed of speech and information density have an impact on how "fast" a language can be.
Both speed of speech and information density have an impact on how “fast” a language can be. georgeclerk

There are a whole bunch of metrics used to measure all this stuff. There’s the total number of syllables per unit time, which you might think would be fairly simple to measure but is not; Pellegrino’s team decided to rely on the “canonical” pronunciation, so the word “probably” would be noted as three syllables even if the speaker pronounces it “probly.”

Then there’s “information density,” which theoretically refers to the quantity of information conveyed per second. This is even tougher; it turns out to be an absolute nightmare to actually define. There’s a technical meaning devised by a guy named Claude Shannon that involves, basically, how quickly a listener can reduce their uncertainty about the message they’re getting. This involves calculations of the number of possible syllables in a language, the relative popularity of each of those syllables, and the probability that a certain syllable will follow another. All the Shannon stuff is kind of abstract and involves a lot of math that, frankly, made my head hurt.

Linguists like Pellegrino have found that there’s an inverse correlation between, basically, how many syllables you can cram into one second and how much information you can cram into one second. Japanese, for example, has an extremely high number of syllables spoken per second. But Japanese also has an extremely low degree of complexity in its syllables, and much less information encoded per syllable. So the syllables come out at a faster rate, but you need more of them to convey the same amount of information as a slow language, like, say, Vietnamese.

But you can also argue that a language like Vietnamese, or even English, is wildly more efficient than Japanese. Japanese syllables contain, mostly, a consonant followed by a vowel, like ko, and Japanese also only has five vowels. English, though we have five letters to represent vowels, has around 20 different vowel sounds. Just by using “A” in different places we can get the vowel sounds in “cat,” “can,” “cane,” “calm,” and a bunch more. Single syllables in English can be extremely complex: the word “strength” involves big annoying clusters of consonants. Vietnamese goes a step further, adding tones, so the tune or pitch of a syllable can also carry value. (Japanese has a system of emphasizing some syllables but is not generally regarded as a tonal language.) Generally speaking, the more complexity we can cram into a syllable, the more information it carries. Japanese is faster than English—around 12 syllables per second, maybe even a couple more for an especially fast speaker—but if English can convey the same information in five syllables, is Japanese really “faster”?

Slow down!
Slow down! Erdark/Getty Images

The concept of how much “information” is disclosed in a certain syllable is pretty wooly, too. Languages are messy, inconsistent, and redundant. A direct translation of the English sentence “I am” to Spanish would be “Yo soy.” But the “yo” isn’t necessary and, in fact, would usually be omitted.

In Hebrew, there’s no verb for “to be,” so to express that you’re hungry, you would say “אני רעב” meaning “I hungry.” That Hebrew one is a good example, because the word for “hungry” actually has a gender involved; a woman would say “אני רעבה”, which adds an extra syllable, but also extra meaning. For a man, the English and Hebrew have the same number of syllables, but to actually convey all the information in the Hebrew, the English would have to be more like “I, a man, am hungry,” which is much longer.

The amount of information can sometimes get even more dense. In the Paamese language, spoken on an island in Vanuatu, possessives can include information on the relationship between the speaker and the object. “My coconut” is not simply “my coconut.” The word for “my” could mean “my coconut, which I intend to eat,” or “my coconut, which I grew,” or “my coconut, which I intend to use in my household in some way other than eating or drinking.” This is a dramatically more efficient use of space than the English version! Is it, therefore, in some sense, “faster”?

Even in English, we can contract “I am” to “I’m,” though many contractions don’t actually save syllables (“shouldn’t” and “should not” are both two syllables). It is, in all languages, possible to delete quite a lot of syllables and still be able to convey information. Languages tend to be encoded with a lot of redundancy, but that does serve a purpose. Redundancy allows for understanding even if the listener isn’t used to the speaker’s accent, or can’t hear the speaker perfectly, or isn’t paying attention. If you edit a sentence down to the absolute bare minimum, it would take a pretty fair amount of concentration, and the right circumstances, to understand and maybe even make some educated guesses as to what the speaker is trying to convey.

In Vanuatu, a couple of syllables can say an awful lot about a coconut.
In Vanuatu, a couple of syllables can say an awful lot about a coconut. Lidiia Kozhevnikova/Shutterstock

This is all to say that there are so many variables that it probably isn’t possible to declare a language the fastest. But it is possible to examine the question from different angles, like a tailor measuring a client for a suit, and get some really interesting information.

Pellegrino, along with a few other researchers, released a paper in 2019 that received a great deal of attention among the admittedly small cohort of people who understand Claude Shannon’s math. The paper found that, in terms of sheer number of syllables spoken per second, the fastest languages of the 17 studied were Japanese, Spanish, and Basque. The slowest were Cantonese, Vietnamese, and Thai.

But! Just to offer a couple of explanations: All three of the fastest languages have only five vowels. The three slowest have upwards of 20, and all are tonal, meaning that there is a gigantic number of possible syllables in those languages.

What Pellegrino found is that, essentially, all languages convey information at roughly the same speed when all the factors are taken into account: around 39 bits per second. The higher the syllable-per-second rate, the lower the information density, which creates a trade-off that makes all languages around the same in terms of information rate.

Pellegrino did not look at any languages from a few pretty prominent language groups. The absence of Swahili and Arabic jumped out to some observers, though it probably isn’t feasible to measure all 7,000 or so languages out there. There’s also the basic issue, which Pellegrino acknowledged, that it’s incredibly hard to actually figure out what “meaning” includes. The Shannon stuff that he used isn’t exactly about “meaning,” but a very specific definition of “information” related to uncertainty, which … well, is not perfect, and also my head hurts again.

Another element that might provide some extra data is in what linguists call “prosody,” the intonation and rhythm of speech. Do we include pauses in our analyses? (Pellegrino did not; pauses don’t apply to the specific kind of speed he was looking at.) What about rhythm? Some languages, like, interestingly, Japanese and Spanish, fall closer on the spectrum to having each syllable take up the same length of time. But Japanese also has some pretty elaborate ways to fill uncertain space.

There are so many elements of language that it is impossible for a single metric like “speed” to cover all of these aspects. It’s kind of like asking “Which country is best?” The answer will change depending on all kinds of variables not specified in the question. That’s not to say there’s not some value in attempting to answer it, though.

Anyway, the fastest language is Japanese.

Dan Nosowitz is a freelance writer and editor currently based in Los Angeles who covers language, food, history, science, and whatever else he can think of. You can find more of his work on his website.