How many words do we really know? What would it take to identify and count all the words a person knows? A tough nut to crack, isn't it? Sure, you could dig into a thick, hardcover dictionary, flip through page by page, mark and count all the words you know. But do you really want to? And hey, what about the time it would take? It would be like trying to count all the grains of sand in a handful of sand.
Is there a better way? Yes, there is. Let's start by counting, say, 20 grains, weigh them, and then use a mathematical algorithm to find the number of remaining grains based on their weight. In our case, weight refers to the frequency of a word, meaning that common and frequent (i.e. simple) words have less weight, whereas rare and complex words carry more weight. We've created a counter and "scales" for you, so you don't have to bother with all that weight-math stuff.
Take the Test and Find Out the Number of Words You Know!
If you really want an accurate result, be honest. Do not tick the words that you might have seen or heard once upon a time, and they seem to be familiar (but you have doubts about their meaning). Don't look up words in a dictionary. And don't worry about your time, the test will take only a few minutes to complete. If your vocabulary is big enough, you will have to go through at most 152 words. Take the test and compare your score with other people from around the world.
Check the box for each word whose definition (at least one) you know for sure.
Hint for Windows users: you can navigate through the checkboxes using the Tab key and select with the Space bar. To skip a word hit Tab once again.