Lexicon: a vocabulary-size test that catches you bluffing

01  What Lexicon is

Lexicon estimates how many English words you know. You get one screen of sixty words in a shuffled grid, you tap every word whose meaning you are sure of, and you tap a button. A few seconds later you have a number — something like 23,800 words — a percentile, a tier label, and the rarest word you claimed.

The whole thing takes about two minutes and there is nothing to install. No account, no sign-up, no app; the test and its arithmetic both run in your browser tab. It is free and supported by ads.

The word "test" sets an expectation the format does not meet. There are no questions and no right answers, nothing is timed, and you are never asked to define a word — only whether you know it. The interesting part of the design is what happens when your answer to that is optimistic.

02  The fifteen fake words, and why they are there

Every pack of sixty hides fifteen invented words. They are built to look like English — plausible letter strings with plausible endings, the kind of thing you could half-believe you once read in a novel. They are not in any dictionary. They are ours; we made them up.

This is the answer to the obvious weakness of any self-report test: nothing stops you ticking words you have merely seen before, and a confident over-claimer would sail to a flattering number. The traps give the test something a multiple-choice quiz cannot measure — your calibration, whether you know what you know.

The tally of traps you fell for becomes a false-alarm rate, and it is subtracted from your hit rate in every band. Fall for five of the fifteen and the result is marked unreliable, with a note telling you to try again and only tap words you are truly sure of. Fall for all fifteen — tap everything on the board, the pure guesser — and the correction zeroes the run completely: zero words, the lowest tier, and the same advice. There is no route to a high score by bluffing. Bluffing is the one thing the format is built to catch.

03  How the number is built

The forty-five real words in a pack are not equal, and this is where the estimate gets its shape. They are sorted into five frequency bands, running from words a young child knows at one end to words most adult readers would have to look up at the other. Nine words from each band, shuffled together with the traps so you cannot tell which is which.

Each band stands for a slice of the language, counted in words: 2,000 for the commonest band, then 6,000, 12,000, 15,000 and 15,000 for the rarest. Those weights add up to 50,000, which is why the estimate never goes above it. The distribution matters more than the total. The rarest band on its own is worth 15,000 — nearly twice the two commonest bands put together. Knowing water, house and friend contributes almost nothing to the number; the rare end is where the whole estimate is made.

So the score works band by band: how much of each band you recognised, reduced by your false-alarm rate, multiplied by what that band is worth, and added up. A realistic run — everything in the three commonest bands, seven of nine in the fourth, four of the rarest, and two traps marked by accident — comes out at 23,846, which the screen rounds to 23,800, for the 30th percentile and the tier we call Word Collector. Recognise all forty-five real words without touching a trap and you land at the ceiling: 50,000, the 99th percentile, Word Wizard. Mark nothing at all and you get zero, which is also what marking everything gets you.

04  The age bands, and what a percentile is comparing you to

Before you press the button you can optionally pick an age band — under 18, 18–24, 25–34, 35–49, 50–64, or 65 and over. One tap, and tapping it again clears it. Skipping it is fine.

Age does not change your word count. It changes who you are being compared against, which is a fairer question than it first looks, because vocabulary keeps growing for decades. A 25-year-old and a 60-year-old who both score 23,846 have not done the same thing, and Lexicon judges them against different bars: that same run reads "bigger than 30% of English speakers" with no age given, "bigger than 33%" if you say you are 20, and "bigger than 24%" if you say you are 65. Older speakers are held to a higher standard, which is the only direction that makes sense.

05  The result card

The payoff is a card: a portrait image, 1080 by 1350, carrying your number, the percentile line, your tier and the rarest word you claimed. It is drawn on a canvas inside your own browser, with no server involved in rendering it, so it comes out identical whether you are online or not.

Three buttons sit under it. Download card saves the PNG. Share result hands the image to your device's own share sheet, so it arrives in a messages thread as a picture rather than a link; if the browser cannot share files it copies the text instead and says so. Copy link copies the plain address. Then there is the button that matters if you enjoyed the first run: Test again with a fresh pack.

06  Five runs, three hundred words, and the only thing Lexicon stores

There are five packs of sixty words, and no word appears in more than one of them — three hundred different words across the full set. Press Test again and you get a different pack, not the same sixty reshuffled. That is deliberate: one pack is a small sample of a very large language, so any single score is noisy, and an average of two or three runs is a much steadier picture.

About your privacy, concretely: the only thing Lexicon writes to your device is which pack you are on, so that the next run is a new one. Nothing about the words you tapped, your score or your age leaves the browser, because none of it is ever sent anywhere in the first place. Clear your browsing data and even that one number is gone.

07  What the number is not

It is a fun estimate and should stay one. Your real vocabulary depends on how you define knowing a word — recognising it, using it correctly and defining it under pressure are three different skills with three different counts — and a sixty-word sample cannot resolve that. The bands, the weights and the percentile curve are our editorial judgement about what feels plausible, not the output of a validated instrument.

None of which stops the number from being interesting: it is a rough reading of a real thing about you, it takes two minutes, and unlike most things online it gets less flattering the more you exaggerate. Share the card if you like what it says — just do not put it on a CV.

08  Questions people ask

How many words does the average person know?

A widely cited figure from vocabulary research is roughly 42,000 lemmas — dictionary base words — for a typical adult native English speaker by age 20. It moves a lot depending on what you count, so treat it as an anchor rather than a fact. Lexicon caps its own estimate at 50,000, the top of the range it considers believable.

Is the vocabulary test free, and do I need an account?

Free, and no account. The test is ad-supported, runs entirely in your browser, and has no sign-up, no install and no paywall. There is nothing to log into and nothing to come back to except the next pack of words.

How accurate is a vocabulary size test like this?

It gives a playful ballpark from a sixty-word sample, not a measured result. Lexicon's bands, weights and percentile curve are our own calibration, chosen to feel credible and entertaining rather than to match a published norm. The estimate is at its most reliable for the middle of the range and least reliable at the extremes.

Why did I score zero words?

Almost certainly because you marked too many of the invented words. The guessing correction subtracts your false-alarm rate from every band, so tapping everything on the board — real and fake alike — cancels out to nothing. Marking nothing at all gives you the same zero for the opposite reason.

Do you store my answers or my result?

No. The test and its arithmetic run in your browser and nothing you tap is sent to a server. The only thing Lexicon saves on your device is which of the five packs you are on, so that pressing Test again gives you a fresh pack rather than the same one.

Can I take it again without seeing the same words?

Yes. There are five packs of sixty words and no word appears in more than one, so you can take the test five times — three hundred different words — before anything comes back around. That is also the honest way to use it: take two or three runs and average them rather than trusting a single score.

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