What Does Hindsight Is 20/20 Mean?

If you’ve ever come to the realization that the great idea you had wasn’t so great after all—once you had already acted on it, and it was too late to change things—you’ve experienced the truth expressed by the idiomatic and proverbial phrase hindsight is 20/20. Read on to learn all about this popular saying.

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What Does Hindsight Is 20/20 Mean?

To get the meaning of this phrase, you first need to know the definition of the word hindsight: the perception or understanding of an event/situation after it has occurred. You also need to know the definition of 20/20: These numbers pertain to eyesight and are used to describe good, clear vision. Putting the two terms together, we can determine that the phrase hindsight is 20/20 means that things become obvious about an event or situation after it has happened; that you can see things clearly about and evaluate your choices once you’ve made them, in a more complete way than you can beforehand. In other words, you can only fully understand an incident once it has passed. Typically it is used to convey that when we look back at or reflect on a situation or event, we see how we could have done things differently, and usually better. To use another saying, it often describes learning a lesson the hard way.

Here are some example sentences using the expression hindsight is 20/20:

  • I can’t believe I dated Adam! He seemed so wonderful at first but turned out to be such a manipulative jerk. As they say, hindsight is 20/20. 
  • Hindsight is 20/20: Now that we lost the competition, I see how our strategy for winning was flawed from the get-go.
  • I should have checked my purse before I left the house, but hindsight is 20/20. I thought my wallet was in there but it wasn’t, so I wasn’t able to pay for my groceries at the store.
  • My friend was so upset about a bad decision she made recently, but I told her not to beat herself up. I reminded her that hindsight is 20/20 and that she thought she was doing the right thing when she made her choice. 

You’ll also often see or hear variants of this expression, including hindsight is always 20/20 and 20/20 hindsight. The 20/20 in the expression can also be spelled out, as twenty-twenty.

The Etymology of the Expression

As mentioned above, 20/20 has to do with vision and comes from the field of ophthalmology. The numbers refer to visual acuity, or the clarity and sharpness of eyesight. 

An ophthalmologist measures visual acuity using an eye chart. The most commonly used eye chart is the Snellen chart. If you’ve ever had an eye exam, you’ll know this diagnostic tool: It features 11 rows of capital letters. From top to bottom, the letters get smaller and the rows feature more and more letters. To test your visual acuity, you cover one eye and read the smallest line of letters you can distinguish at a distance of 20 feet (sometimes a mirror is used in small offices to artificially create the distance if you cannot physically stand 20 feet from the chart). 

If you have 20/20 vision, you have normal acuity and are considered to have good, normal vision. When you’re standing 20 feet away from the eye chart, you can clearly see each row of letters. If you have 20/30 vision, the letters you see clearly on the chart at 20 feet, the average person can see clearly from a distance of 30 feet. Meaning, you have worse visual acuity and strain more than the average person to see things clearly at a distance. 20/20 vision isn’t perfect vision, however, as it only takes into account acuity. Peripheral vision, depth perception, and other aspects of eyesight are also critical to vision. But the point being, that a person with 20/20 vision has good eyesight and can see things sharply and clearly at a distance. Because it’s the standard for good visual acuity, it’s used in this phrase to indicate that when we have distance from a situation, we can understand it clearly and see what we could have done differently.

No one knows for sure exactly when this phrase was first used, but we do know the Snellen eye chart was developed in 1862. So it’s safe to say the expression came into use after that year.

Understanding Idioms and Proverbs

Hindsight is 20/20 is considered both an idiom and a proverb. An idiom is an expression with an intended meaning that typically can’t fully be understood just by looking at the individual words that comprise it. Even if you’ve never heard the term idiom, you have most likely heard many idiomatic expressions. Here are just a few of the most common idioms used today:

You’re in hot water.
His boss gave him the ax.
It’s time to face the music.
You’ve hit the nail on the head.

If you took the first example literally, you’d think it was describing a person standing in a bathtub full of hot water, perhaps. But the expression is actually used to describe a person who’s in trouble. Likewise, rather than literally being handed a tool for chopping wood, if you get the ax from your boss, it means you’re getting fired. It’s time to face the music means that it’s time to come to terms with the consequences of your actions. And when someone has hit the nail on the head, they’ve gotten an answer exactly right or done something exactly as it should have been done.

Now that you know the meaning of 20/20 in this phrase, you can see that the phrase can’t be taken literally: Hindsight is not the same thing as a normal visual acuity score on an eye exam. But they do pertain to each other. The comparison between hindsight and a 20/20 score is a metaphor: The expression is meant figuratively to say that we can see things sharply or clearly after they’ve happened, and thus once an event or situation has passed, we can learn from it.

A proverb is a short, common phrase or saying that imparts advice or shares a universal truth. Synonyms of the term proverb include adage, aphorism, and maxim. Here are some additional examples of well-known proverbs:

Blood is thicker than water.
A picture is worth a thousand words.
Beauty is in the eye of the beholder.
Don’t judge a book by its cover.

Discover many more idioms and proverbs here.


The idiomatic and proverbial expression hindsight is 20/20 is used to convey the understanding one has about an event or situation only after it has occurred. In other words, it expresses the full clarity we’re able to have about a past decision or action, clarity we can’t have before a choice is made. When we look back at a situation or reflect on a decision, we can see what we should have done differently, and usually what we could have done better to improve the outcome. The 20/20 in the phrase is a reference to a normal visual acuity score, measured by an eye doctor using an eye chart.