All articles · Published 2026-08-06
How Many Words Do You Need for TOEIC? We Did the Math — and Decided Not to Give You a Number
It's probably the question we get asked most, and the internet's answers run from five thousand to "20,000 must-know words." So we counted every single word in six full mock exams — 1,200 questions — and reached two conclusions. First: the number everyone quotes ("score X needs Y words") cannot actually be computed — not by us, not by anyone. Second: a different question turns out to have a surprisingly clear answer. Vocabulary is finishable, and the finish line is closer than you think. This post lays out the whole calculation, all the numbers, and how they changed the vocabulary features in the app.
The Question Everyone Asks
"How many words do I need for a TOEIC score of X?"
Search for it and the answers pile up: some say 5,000, some say 7,000, and some vocabulary books print "20,000 must-know words" right on the cover. These numbers differ by a factor of four, yet every one of them is stated with total confidence.
We decided to do the math ourselves. We had the right material on hand: six complete mock exams — 1,200 questions, with every listening script and every reading passage — the same reference corpus we used to calibrate question difficulty in the Difficulty Overview. Big enough, real enough; counting it word by word is just an engineering problem.
How We Counted
The method itself is no mystery: extract every word in the six forms, reduce each to its base form (so made is charged to make's account), look up its frequency rank in English corpora, then build a model — assume a test-taker "knows the most common N words," simulate their performance on every question, and convert that to a TOEIC score. Draw the curve, and "how many words for score X" should fall right out.
Sounds scientific, right? Here comes the problem.
Why "Score X Needs Y Words" Cannot Be Computed — by Anyone
A model like this can't avoid a few assumptions. When you hit an unknown word, how much should your odds of answering drop? Does an unknown word in the question stem hurt as much as one buried in the passage? What's the probability you guess it from context?
Nobody knows the correct values for these assumptions — the research literature doesn't say, and the test maker has never published them. And if you merely nudge them within the range of "perfectly defensible," the answer for, say, a 750 slides from around five thousand words to over ten thousand — nearly a factor of two.
The conclusion is awkward, but worth stating plainly: anyone who tells you "score X takes Y words" has picked one answer out of a wide field of equally possible ones. The only difference is that some don't know they're picking, and some know but don't say. We'd rather be neither, so we're leaving that number to others.
A Better Question: Can Vocabulary Be Finished?
Having given up on "how many words for score X," we asked a question that needs no assumptions at all — you just count: if you learn everything worth learning, how many unknown words are left on the exam?
Define the "known set" as a high-school graduate's basic English (about five thousand common words) plus all 3,834 words in the Handy 990 vocabulary bank. Check that set, word by word, against the six mock forms:
| What we counted | Result |
|---|---|
| Questions where you know every word in the stem and options | 85% |
| Of the remaining 15%, questions missing exactly one word | 81% |
| Unknown words left across all six forms, 1,200 questions | 215 |
| Of those 215, words appearing only once in all six forms | 99% |
In other words: once you finish the bank, what remains on the exam isn't "words you haven't studied yet" — it's "words even the exam itself only uses once." The kind you shrug at in the test hall and answer around from context. Past this point, piling on more vocabulary has a marginal return on your score that is close to zero.
So here is the better answer: vocabulary is finishable. And once it's finished, what's holding your score back is no longer vocabulary — it's grammar, listening speed, and reading comprehension, each with its own practice and its own place in the app.
So We Decided Not to Do Something
The same analysis produced a list of roughly four hundred words that real exam questions used but our bank doesn't include. Adding them would have been an afternoon of work — and we decided not to.
Because the data is unambiguous: the vast majority of those words appear once or twice across all six forms. Adding them would mean making you memorize a few hundred words you'll almost never meet, turning "finishable" back into "unfinishable" — trading the finish line for completeness. We think that's a bad trade.
Others hand you a 20,000-word list. We hand you 3,834 words, plus the full evidence for why that's enough. The small size is deliberate.
Three Changes in the App
This analysis wasn't for show — it changed three things directly:
1. The vocabulary checkup now tells you how far the finish line is. After the placement checkup (see How Handy 990 helps you learn vocabulary), the results page is no longer just a level — it's a sentence that means something: "With your current vocabulary, about X% of real-exam questions contain no unknown words; learn the remaining N words to reach 85%." That N counts down — because it genuinely has an end.
2. Finish the whole bank and you graduate. Completing the entire vocabulary bank unlocks the "Vocabulary Graduation" achievement. The graduation screen says exactly one thing: the vocabulary quest is complete, and your next points are in grammar and listening — then takes you straight there.
3. A new explainer page: "Why are these words enough?" Every number in this post ships inside the app, checkable anytime. We want you to feel at ease because you can see the evidence — not because we said so.
An Honest Footnote
As always, the boundary lines. "Knowing every word" is not the same as "answering correctly": paraphrase, grammar traps, and listening speed all still need practice — which is exactly why the rest of the app exists after vocabulary graduation. Vocabulary works like a ticket: without it you can't get into the stadium, but holding a ticket doesn't mean you can read the game.
We just want you to be certain of one thing: the vocabulary stage has a finish line, and you can reach it.
The next time someone tells you, with total confidence, "score X just takes Y thousand words," you can tell them: that number can't be computed — not even by the people who write the exam.
The numbers in this post come from a word-by-word comparison of six full mock exams (1,200 questions) against the Handy 990 vocabulary bank; the corpus is the same reference set used in the Difficulty Overview, and as usual we publish aggregate statistics only. Questions about the methodology are welcome by email.