The vocabulary acquisition rate calculator shows how long it takes to build your target vocabulary size based on your daily learning pace and a forgetting curve adjustment. Use it alongside an Anki deck to plan your language vocabulary goals.
Vocabulary Milestones
How to Use the Vocabulary Acquisition Rate Calculator
Building vocabulary is the core engine of language learning. This calculator helps you set realistic milestones by accounting for the forgetting curve — the well-documented finding that without spaced review, roughly 30% of newly learned words are lost over time.
Understanding the Forgetting Curve Adjustment
The calculator applies a 70% retention factor to your daily word count. If you study 15 new words per day, approximately 10–11 of those words will be retained long-term with spaced repetition practice. This is why using Anki or another SRS tool is essential for vocabulary building — passive review without spaced intervals leads to much lower retention.
Setting Realistic Targets
B2 (8,000 words) is the most searched target because it's the level where authentic content becomes fully accessible. If you already know 500 words from previous study and learn 15 new words/day, reaching B2 vocabulary takes approximately 4.5 years at 70% retention. Increasing to 20 words/day brings this to about 3.4 years.
Combining with Immersion
Explicit vocabulary study (flashcards) works best in combination with immersion reading and listening. Seeing a word in context 10–15 times cements it in long-term memory faster than review cards alone. Aim for 70% SRS study + 30% authentic reading/listening for optimal vocabulary acquisition speed.
FAQ
Is this vocabulary calculator free?
Yes, completely free with no signup required. All calculations run locally in your browser.
How many words do you need for each CEFR level?
Approximate vocabulary sizes: A2 ≈ 2,000 words, B1 ≈ 4,000 words, B2 ≈ 8,000 words, C1 ≈ 16,000 words. These are receptive vocabulary estimates (words you recognize); productive vocabulary (words you use) is typically 50–60% of this.
What's a realistic number of new words to learn per day?
10–20 new words per day is sustainable with spaced repetition. 20 new words/day = roughly 600 new words/month. At 70% effective retention, that's about 420 retained words/month.
What is the forgetting curve adjustment?
Ebbinghaus's forgetting curve shows that without review, people forget roughly 50–80% of new information within days. With spaced repetition (Anki), effective retention is roughly 70% of newly learned words over time. The calculator applies this 70% adjustment to estimate retained vocabulary.
Does this count words learned through immersion?
This calculator counts explicitly studied vocabulary (flashcards, word lists). Immersion also builds vocabulary incidentally, but at a less predictable rate. Total vocabulary growth from immersion alone is roughly 1–2 new words per hour of authentic listening/reading at B1+ levels.
Why is B2 vocabulary (8,000 words) so much bigger than B1 (4,000)?
B1 vocabulary covers everyday conversational topics (family, work, food, travel). B2 requires vocabulary for abstract discussions, opinions, media, and a wider range of domains. The jump from B1 to B2 is often described as the hardest step because authentic content suddenly becomes accessible.