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Which Is Correct: “On Accident” or “By Accident”?

Accidents happen all of the time, no matter how hard we try to avoid them. You may be aware of two different phrases when accidents inevitably occur: “by accident” and “on accident.” Still, which one is correct? 

The correct adverbial phrase to use when explaining how an accident happened is “by accident.” While you may hear “on accident” in spoken English, you should never use this phrase in writing, and most grammarians agree that it is incorrect regardless. Still, both phrases mean the same thing: something happened accidentally or not on purpose. 

Continue reading to learn more about the meaning of and difference between “by accident” and “on accident” and why you should choose one over the other. 

What Does “By Accident” Mean? 

The adverbial phrase “by accident” means that you or someone else did something accidentally, without intending to, or not on purpose (source).

An accident happens when you do not plan or intend something to occur, and it generally causes harm, damage, or injury to someone or something (source). Often, accidents happen by chance, and there’s not much we can do to control or stop them, despite some occurring due to carelessness or ignorance.  

One example to consider is a car crash. While nearly all car crashes are unplanned, unintentional “accidents,” they often occur due to human error or negligence, such as looking down at a phone to check a text message.  

But some accidents do happen by chance. And in that way, they can either be good or bad, though most times, we would use the word with a negative connotation, such as in “My cat jumped onto the counter just as I was pouring milk, causing me to drop my glass by accident.”  

A positive connotation is one in which the feeling or emotion attached to the word is one of optimism or happiness, such as in “I met my husband by accident when we bumped into one another at the train station” (source).

You’ll note the preposition “by” precedes “accident” (a noun) in both examples. Together, these two words create an adverbial phrase, which we’ll explain more shortly. But the preposition “by” here precedes the noun (accident). It shows how something occurred — in this case, accidentally. 

Remember that you would only use the word “by” as a preposition when you follow it with a noun (such as with the word “accident). We’ll also talk more about the broader concept of preposition types toward the end of this article. 

But first, let’s break down why it’s grammatically correct — and preferable — to say “by accident” over “on accident” in both speaking and writing.

Is It Grammatically Correct to Say “By Accident”?

It is grammatically correct to say that something happened “by accident.” The phrase is an adverb phrase and means the same thing as the traditional adverb, “accidentally.” 

You’ll probably recall that an adverb is a word or part of speech that can modify or tell you more about a verb, an adjective, or another adverb. Often, adverbs modify verbs because they explain how something happened.  

You may also have learned that many adverbs, including “accidentally,” end in -ly. In this way, they are easy to spot — but remember that not all adverbs end in -ly. The easiest way to differentiate an adverb from other parts of speech is to identify if the modifying word answers “when?” “where?” “how?” or “to what extent?”

When you say, “by accident,” you are simply using an adverb phrase instead of a single adverb to modify a verb, showing how something occurred — in other words, whatever happened was not on purpose.

An adverb or adverbial phrase is when two or more words function together as an adverb. In this case, adding the preposition “by” before the noun “accident” further explains how you or someone else did something.   

How Do You Use “By Accident”?

You can use “by accident” the same way you use “accidentally.” As part of a full sentence, you’ll use the adverb phrase to show that you or someone else did something that was not purposeful. You can also use the short phrase in isolation as part of a dialogue or conversation.

Remember that “by accident” is a phrase and not a complete sentence, even though it expresses a complete thought. So, while you will not use the phrase in isolation in writing, you will often find that in response to a question, you can use “by accident” as a response without adding anything else to it.  

Here is an example:

  • Question: How did the glass break?
  • Response: “By accident.”

If you use the phrase in writing, you’ll want to be sure to create a full, complete clause or use it as part of a planned dialogue with proper punctuation. 

When Can You Use “By Accident”?

You can use “by accident” to respond to someone’s inquiry as to how something happened or when explaining the reason for an unfortunate event. Remember, too, that you can also use the phrase with a positive connotation.

Earlier, we said that mistakes or accidents happen all of the time. Sometimes, they are unintentional and happen by chance. Sometimes, you may do something that hurts someone else’s feelings even though it was not purposeful. And sometimes, good things happen by accident, too.

In each context, using the phrase “by accident” simply explains how the event or situation came about.  

If you hurt someone’s feelings, you may want to apologize and explain that you did so “by accident.” Also, if you spilled a glass of milk because the glass fell from your grasp, you can say that it happened “by accident.”

In general, you can use this phrase any time something happens that was not on purpose — whether it was a positive or negative event. 

Using “By Accident” in a Full Sentence

Using “by accident” in a full sentence means that you’ll need to add a subject (noun or noun phrase) as well as a verb that you will modify with the phrase “by accident.” 

Remember that because “by accident” is an adverb phrase, it needs something to modify. And, because all proper sentences need a subject to be complete, we need to add more to this phrase to create a complete, full sentence. 

Here are some examples:

  • People meet by accident when a chance event or change of circumstance happens.
  • My daughter broke a cherished possession by accident

The first sentence above explains how people meet — by accident. The adverb phrase modifies the verb, “meet.” To understand why this is an adverb phrase, remember that it answers “how” an event happened. In this case, “how do people meet?” 

In the second sentence, “by accident” modifies the verb “broke,” explaining how the young girl broke the cherished possession.

In What Context Can You Use “By Accident”?

You can use the phrase “by accident” in any context where you or someone else did something accidentally or in any context where something occurred that was not purposeful. 

There are quite a few different contexts where things happen accidentally, including traffic accidents, spills, falls, and, even as we stated earlier, in situations with positive connotations like a chance meeting of friends. 

It doesn’t matter whether the connotation of the word is positive or negative. What matters is that you only use the phrase when something genuinely happens accidentally.  

Is It Grammatically Correct to Say “On Accident”? 

It is not grammatically correct to use the phrase “on accident,” despite the fact that you may hear it in spoken English. The preposition “on” is not the preposition you should choose; instead, you should use “by.” 

If you are wondering why you hear people say that something happened “on accident” even though it is not correct, it’s because many confuse or compare this phrase with another phrase that is its opposite. 

The phrase “on purpose” is similar to “on accident,” but rather than meaning something happened accidentally, it means that you or someone else did something purposefully. And while the phrase “on purpose” is correct, “on accident” is not. You should always use “on purpose” and “by accident.” 

“On” is also a preposition that you can use in many ways, including to express time or to show placement. And unfortunately, there are many grammar rules and conventions that don’t seem to make much sense, especially if you are learning the language for the first time. 

In What Context Can You Use “On Accident”? 

Even though both “on accident” and “by accident” mean “accidentally,” the only context in which you can use “on accident” is in conversation as many do mistakenly, but remember that it is not technically correct. 

You may hear small children say that they did something “on accident.” This is because they learn the language just as anyone else learns it. Once you understand the phrase “on purpose,” it makes sense that the same preposition would fit when you want to say that you did something accidentally.

But that is not the case for this phrase. There generally is not an acceptable context to use “on accident.” Still, if you do use it, your listeners will understand your meaning, despite it being incorrect, technically speaking. 

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When Not to Use “By Accident”

You should not use “by accident” unless something occurs accidentally. You should never use the phrase if you have done something with intention, even if the outcome is not what you were hoping for.

While you may experience situations where someone says that they did something by accident, even though you know that they did it on purpose, you should not do the same. This is not genuine and will only result in hurt feelings. 

The only other time that you should avoid the phrase is in writing. If you are writing and not using dialogue in your writing, you will need to write a full sentence using the phrase correctly as a modifying phrase in conjunction with a proper subject (noun) and verb or verb phrase. 

The phrase is neither formal nor informal, particularly. So, you can use it in various genres of writing and when speaking to different categories of people and acquaintances.  

What Can You Use Instead of “By Accident”?

If you find yourself forgetting whether you should use “on” or “by” before “accident,” you can use the word “accidentally” instead. There are other synonymous words you can choose as well.

Synonyms for “by accident” can include any of the following:

  • Accidently
  • Mistakenly
  • Unintentionally
  • Carelessly
  •  Unknowingly
  •  Inadvertently 

Remember that the connotation for some of these synonyms differs slightly from that of “accidentally” or “by accident.”  Be sure you are aware of the context before you choose a synonym.  

For example, to be “careless” or to do something “carelessly” means that you or someone else did something without being careful; thus, it was an accident, but there is a stronger, more negative connotation attached to this synonym.  

Preposition Types

There are different types of prepositions, but they generally show the relationship between the words they are connecting, whether through time or space. There are simple or single-word prepositions, double prepositions, compound prepositions, participle prepositions, and phrasal prepositions. 

Simple prepositions are single words that define a relationship between words, phrases, or even clauses. Some examples include: “for,” “by,” “on,” “in,” “off,” “at,” and “to.”

Double and Compound Prepositions

Double prepositions are fairly simple as well, but they include prepositions with two words or two simple prepositions combined to create a single word, such as “into,” “onto,” “without,” or “within.”

Compound prepositions are slightly different from double prepositions in that they are two or three-word prepositions that function as a single preposition. Some examples include “according to,” “as of,” “because of,” and “next to.” Three-word preposition examples include “as far as,” “in addition to,” and “on top of.”

Participle Prepositions

Participle Prepositions also show a relationship, connecting two words or ideas in a sentence. It is essentially a participle that functions as a preposition and ends in -en or -ing. 

You may recall that a participle is a word that you would form from a verb but actually acts as an adjective. In this case, the participle acts as a preposition instead. Examples of participle prepositions include “considering,” “during,” “regarding,” “excluding,” and “concerning.” 

Phrasal Prepositions

Finally, phrasal prepositions are a combination of a preposition, sometimes a modifying word, and an object. This can get pretty confusing because some say that a phrase preposition differs from a prepositional phrase, the latter consisting of a preposition and its object, and the former another variation of a compound preposition.

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Remember that prepositions are integral parts of understanding the English language. They show a relationship between words, whether that relationship shows time, place, direction, or an idea between two things. They also usually precede a noun to show its relationship to another word or part of your sentence.

Final Thoughts

Like many things in the English language, phrases like “by accident” and “on accident” can be confusing for many, especially because there is not a particular rule governing the reason you should use “by” and not “on” in conjunction with “accident.”  

Conversely, you should use “on purpose” and not “by” purpose. Again, there’s no rhyme or reason other than to say that one is more prevalent, and we understand it to be correct versus the other.

If you’d like to learn more about common phrases in English and how to use them correctly, take a look at “‘In Accordance With’ or ‘In Accordance To’: Which is Correct?” next.