Kilo Lingo

Estimator

FSI time-to-fluency estimator

An honest estimate of how long it will take you to reach a CEFR level in your target language, based on the US Foreign Service Institute's category data and your weekly study hours. The numbers are guidance, not a guarantee.

5 h

Estimated time to reach B1

13-20 months

FSI Category I

Based on roughly 288 to 432 total study hours at 5 hours/week. The low end assumes input-rich practice (reading, listening); the high end is the FSI classroom figure.

How this works

The US Department of State's Foreign Service Institute publishes broad ranges for how long it takes a native English speaker to reach "general professional proficiency" (a 3/3 on the Interagency Language Roundtable scale, roughly CEFR B2-C1) in each language category. Category I is closest to English (Spanish, French, Italian); Category V is furthest (Arabic, Mandarin, Japanese, Korean). This tool linearly scales the FSI hours range to your weekly study commitment and your target CEFR level.

The estimate is structural, not personal. Adult learners with more reading and listening practice hit each level faster than the FSI number; learners doing only an app finish later and plateau sooner.

Sources and assumptions

  • FSI hour ranges are from the US Department of State (Foreign Language Training). FSI's published figures are the upper end of each range here. The lower end is an adjustment of around 20-30% to reflect adult learners who supplement classroom time with input-rich practice (extensive reading, listening, conversation); it is not an FSI number.
  • CEFR mapping. FSI's "general professional proficiency" maps to approximately CEFR B2-C1. A2 and B1 figures here are interpolated downward (35% and 60% of the B2-C1 hours respectively); C1 is scaled up (140%). See the Council of Europe's CEFR Global Scale for the level descriptors.
  • Category split. FSI's current public scheme has four categories; this tool keeps the older five-category split that separates "hard" languages (Russian, Vietnamese) from "super-hard" languages (Mandarin, Arabic, Japanese, Korean), because the hour difference between the two groups is large.