The Immersion Roadmap
Calculate your path to fluency. Based on FSI benchmarks and 1000s of hours of data.
By Dec 31, 2026, you'll have immersed for 507 hrs at this pace.
Language & Levels
Beginner (No Knowledge)
N1 (Advanced/Fluency)
Study Parameters
How closely related is this to languages you already know?
Method & Goals
Passive Listening is slower but easier to sustain.
Active Fluency requires +25% time for output/speaking drills.
Media Breakdown
* Average Lengths: YT (10m) • TV (24m) • Podcast (45m) • Film (100m) • Book (300m)
The Science Behind the Math
This calculator isn't a random guess. It's built on 70+ years of linguistic research from the U.S. FSI, academic studies on vocabulary acquisition, and modern immersion efficiency data. Read the full deep dive.
Base Hours: FSI Standard
We use the Foreign Service Institute (FSI) difficulty rankings as our baseline. The FSI has trained US diplomats for decades, gathering precise data on class hours required for proficiency.
- Category I (e.g. Spanish): ~600-750 hours
- Category V (e.g. Japanese): ~2200 hours
Efficiency: Reading-While-Listening
Dr. Paul Nation's research (Victoria University of Wellington) on the "Four Strands" of language learning highlights the power of bi-modal input.
Combining audio with matching text (RWL) creates a 1.4x efficiency boost in vocabulary retention compared to listening alone. It bridges the gap between the high retention of reading and the natural flow of listening.
Why the "Active Fluency" Penalty?
Linguistic research consistently shows that receptive fluency (understanding) always precedes active fluency (speaking). Children understand language months before they speak.
Bridging the gap from "Input Only" to "Active Fluency" requires output drills (speaking/writing). We add a conservative 25% time surcharge to account for this necessary activation energy.
Key Research Sources:
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