How does Duolingo calculate its fluency percentage?


There's a lot of discussion been going on in the Language Learning chatroom about Duolingo's fluency percentage. My fluency percentage (as well as many others') seems very inaccurate, so I was wondering what calculations actually go into creating an actual percentage. Is it knowing all of your vocabulary, keeping your skills refreshed, or something completely different?


Posted 2016-05-07T00:13:20.910

Reputation: 5 657

Unless you say how the "fluency percentage" relates to actual fluency, this really is a software question, not a language one. Scores are great for learning (since the first grade...), but you have to say what they mean. – user3169 – 2016-05-07T04:56:09.547

1@user3169: It is indeed a software question. But it's still relevant to many language learners, so I think it's a reasonable question here (and a completely unreasonable feature of Duolingo) – Flimzy – 2016-05-07T12:29:47.537



From an official Duolingo developer,

This is exactly what it sounds like: our estimate of your fluency in the language you're learning. It is calculated based on what words you know, how important those words are, how well you know them, and how likely you are to forget them. It will increase over time as you learn more words and strengthen your skills, but it will decrease if you don't keep up your strength. Since our goal is for this estimate to be as accurate as possible, be aware that finishing your tree won't get you to 100%.

Emphasis mine

Although I do use Duolingo regularly, I would recommend against using your "fluency percentage" as an actual indicative measure of how fluent you are in a language. Not only does the fluency meter not work as it should, Duolingo doesn't realize that knowing just vocabulary doesn't make you fluent in a language.


Posted 2016-05-07T00:13:20.910

Reputation: 5 657

2This is exactly what it sounds like -- I beg to differ. Exactly what it sounds like is snake oil. :P – Flimzy – 2016-05-07T08:25:11.790

@Flimzy I totally agree with you, but I'm only quoting the words of a Duolingo developer :P – fi12 – 2016-05-07T11:39:39.757


From What does my Fluency Score mean?

Fluency measures your mastery of the vocabulary and grammar of a language and your ability to understand and produce the language.

Duolingo estimates your fluency based on your progress through the skill tree and the accuracy of your answers. Because learning a language requires repetition, we also take into account how regularly you practice. Without continued practice, your fluency score will decline, based on our model of how the human brain forgets over time.

With Duolingo, you can achieve a fluency as high as 50-60%, which is equivalent to Advanced proficiency.

Jillian Morhat

Posted 2016-05-07T00:13:20.910

Reputation: 71

Welcome to Language Learning Jillian! – fi12 – 2016-05-09T23:32:54.507