Vocabulary Growth Calculator
Project total vocabulary size by adding daily learning to current vocabulary over a chosen number of days. A simple linear-projection tool for language learners planning realistic vocabulary acquisition timelines.
Last updated: May 2026
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About this calculator
Projected vocabulary = currentVocab + (newWordsPerDay × days). The formula assumes linear accumulation with no forgetting — a useful upper bound for planning purposes. Variables: currentVocab is your current passive vocabulary in the target language (typically estimated by self-assessment tests like LexTutor, Test Your Vocab, or counting known items from a frequency list); newWordsPerDay is the number of new words you commit to learning per day; days is the planning horizon. Edge cases: all values should be ≥ 0; in practice, the linear model overestimates because real retention is incomplete — adult language learners typically retain 70–85% of new words seen via spaced repetition, so 10 new words per day really yields ~7–8 retained, not 10. Reference vocabulary sizes for English: 2,000 word families ≈ enough for everyday spoken conversation; 5,000 ≈ basic literacy; 10,000 ≈ comfortable adult reading; 20,000 ≈ educated native speaker; 30,000+ ≈ broad literary vocabulary. For language learners: A2 ≈ 1,500–2,500 words; B1 ≈ 2,500–4,000; B2 ≈ 4,000–10,000; C1 ≈ 10,000+; C2 ≈ 15,000+. Sustainable learning pace for adults using spaced repetition is typically 10–20 new words/day; aggressive intensive learners (immersion students, professional translators) can hit 30–50/day for limited periods. At 15 words/day with consistent practice, a B1-level learner (3,000 words) needs about 14 months to reach C1 (10,000 words) — matching the typical CEFR-level progression timeline. Always combine vocabulary work with reading, listening, and active production; isolated vocabulary lists are far less effective than words encountered in meaningful context.
How to use
Example 1 — Steady learner. You currently know 5,000 words, learn 10 new words per day, and plan a 30-day study cycle. Enter Current Vocabulary = 5000, New Words per Day = 10, Number of Days = 30. Total = 5000 + (10 × 30) = 5300 words. ✓ Linear projection; realistic retention probably puts you at 5200–5250 actual retained words, but you'll have been exposed to all 300 new entries. After a year at this pace: 5000 + (10 × 365) ≈ 8,650 words — close to lower B2 level for most European languages. Example 2 — Intensive learner. Starting from 2,000 words, committing to 25 new words/day for 6 months (~180 days). Enter 2000, 25, 180. Total = 2000 + (25 × 180) = 6500 words. ✓ A jump from upper A2 to upper B2 in 6 months — aggressive but achievable for motivated learners using spaced repetition and immersion (~2 hours/day total study time). Real retention at this intensity is typically 70–80%, so the actual retained vocabulary after 6 months is closer to 5,500–6,000 — still a dramatic jump enabling literature reading and unrestricted spoken communication.
Frequently asked questions
How big is a typical vocabulary?
Native English speakers typically know 15,000–35,000 word families (a "family" includes a root and its inflected/derived forms). Educated adults are at the higher end; the difference between average and educated speakers is partly the size of low-frequency vocabulary that comes from extensive reading. Children acquire ~1,000 word families per year between ages 6 and 18, reaching ~15,000+ by adulthood with normal education. Foreign-language proficiency levels: A2 ≈ 1,500–2,500 words; B1 ≈ 2,500–4,000; B2 ≈ 4,000–10,000; C1 ≈ 10,000+; C2 ≈ 15,000+. To read most newspaper text comfortably you need ~98% coverage, which requires the top 8,000–9,000 word families. Speaking conversation requires fewer (the top 2,000 covers ~80% of speech). The most important variable is which words you know, not just how many — the top 2,000 most-frequent words give vastly more communicative power than 2,000 random low-frequency words.
How many new words can I realistically learn per day?
Depends on intensity and method. Casual learners (15–30 min/day with spaced repetition) typically retain 5–10 new words/day sustainably. Serious learners (1–2 hours/day) can sustain 10–20/day. Intensive learners (3+ hours/day with immersion and varied practice) can hit 25–50/day for limited periods (weeks to months) before fatigue sets in. The hard ceiling for most adults is around 50/day even with maximum effort; above that, retention drops dramatically as cognitive load exceeds capacity. Spaced repetition systems (Anki, Memrise, etc.) handle the scheduling problem — keeping all those words active in memory through optimally-spaced reviews. Without spaced repetition, "10 new words a day" might mean 80% are forgotten within a week. Reading widely (extensive reading) is the second most-effective method; encountering words in real context strengthens recall and adds nuanced meaning that flashcards alone miss.
Why is vocabulary growth not actually linear?
For three reasons. (1) Forgetting: without continued review, learned words decay following an exponential curve (Ebbinghaus). Even with spaced repetition, 10–20% of new words are eventually lost, so net growth is slower than gross new additions. (2) Saturation: high-frequency words are easy because you encounter them constantly in reading and listening; very low-frequency words (technical terms, archaic, dialectal) require explicit study because natural exposure is rare. So the first 5,000 words come quickly via immersion, the next 5,000 require systematic study, and the 20,000+ range comes only from extensive reading or professional specialisation. (3) Productive vs receptive vocabulary diverge: you can recognise far more words than you can use actively. "Learning" a word usually means receptive knowledge first (recognition in context); productive mastery (using it correctly in your own speech and writing) takes additional practice. Realistic curves are S-shaped: slow start (no foundation), fast growth (foundations enable inference), plateau (encountering only rare new words).
What are the most common mistakes in vocabulary learning?
The first is learning in isolation — words memorised from lists without context are forgotten quickly. Always learn words in sentences or with example uses. The second is over-relying on frequency lists; the most-frequent 2,000 words are essential, but rare and topic-specific vocabulary matters for your actual goals (work, academic, personal interests). The third is treating "passive recognition" as "learned"; you might recognise a word in a multiple-choice test but be unable to recall it when speaking. Productive use is the harder skill. The fourth is bingeing — cramming 100 new words in one session, then forgetting most. Daily small doses (10–20 words) with spaced review compound far better. The fifth is ignoring word relationships (collocations, synonyms, antonyms, families); learning "decision" alone is less useful than learning "make a decision", "tough decision", "indecisive". The sixth is over-using one-direction learning (target → English) without practising the reverse (English → target), which is what production requires.
When should I not use this calculator?
Skip it for languages with non-alphabetic writing systems where "word" is poorly defined (Chinese, Japanese, classical languages); character or radical counts are more meaningful. Don't use it for sign languages or other languages with different basic units; signs, classifiers, and movement units don't map onto "words" cleanly. It's the wrong tool for measuring fluency or proficiency — vocabulary size correlates with proficiency but doesn't determine it; grammar, pronunciation, listening, cultural knowledge all matter. Avoid using it as a primary motivation; tracking words-per-day can become a substitute for actually using the language. The goal is communication and comprehension, not big numbers. Finally, don't treat the linear projection as a promise; real vocabulary growth involves forgetting, plateaus, and unpredictable individual variation. Use it for planning ranges and expectations, not as a target to hit precisely.