“Outside” or “Outside of”? Difference Explained (With Examples)

There are many variations between English dialects. On this page, we are going to look at one of these differences. This is the difference between ‘outside’ and ‘outside of’. As you go through this page, you will see neither is incorrect, but you may want to use one more.

Is It ‘Outside’ or ‘Outside Of’?

It doesn’t really matter whether you use ‘outside’ or ‘outside of’. You would use the word ‘outside’ in British English (which also covers Canada, India, Australia, etc.), while you are much more likely to find the phrase ‘outside of’ spoken in US English.

outside or outside of

The use of ‘outside’ and ‘outside of’ are just some of the countless phrases that can vary depending on the dialect that is being spoken. Although, nowadays, while ‘outside of’ is being used heavily in American English, a lot of Americans are moving towards the use of just ‘outside’.

Both of these phrases are 100% grammatically correct, and they are 100% interchangeable. Although, we do encourage you to use just ‘outside’ wherever possible. Brevity is important when it comes to written and spoken language.


Using the word ‘outside’ without using ‘of’ as a preposition has its roots in British English. You would use the word ‘outside’ if you are pointing out that something is located outside e.g. ‘the parcel is outside the door’. Nowadays, this is the preferred usage.

Remember, we are purely talking about using the word ‘outside’ when discussing the location of a specific object or person here. We are not considering the fact that ‘outside’ can be used purely as a location e.g. ‘the event is being held outside’. In that case, you would never need to use a preposition after the word ‘outside’.

Here are a few examples, so you can see how ‘outside’ is used in a sentence:

  1. You should think outside the box.
  2. The parcel is located outside the house.
  3. I spilled water outside the mug.
  4. You can find the garbage bin outside the door.
  5. It isn’t uncommon for protestors to be outside the government buildings.

Outside Of

The phrase ‘outside of’ is the American English version of just saying ‘outside’. It is mostly only used within the United States, and it has started to fall in popularity. When you say ‘outside of’, you are talking about something being outside of a building or an object.

It is worth noting that while ‘outside of’ is correct, it tends to be avoided by most people nowadays. This is because when writing, you should always try to use as few words as possible. The word ‘of’ is redundant. It serves absolutely no purpose, so it should be eliminated.

Here are ways that you can use ‘outside of’ in a sentence. Remember, in every single case here, you can drop the ‘of’ and still end up with a sentence that reads 100% correctly. In fact, some would argue that dropping the ‘of’ makes for a better sentence.

  1. The mailman left the package outside of the door.
  2. Please wait outside of the room while we discuss your performance.
  3. I waited outside of the doctor’s office for what felt like an eternity.
  4. My work wants me to work outside of the office today.
  5. The garbage fell outside of the garbage bin.

Is It Thinking ‘Outside The Box’ or ‘Outside of The Box’?

Both ‘outside of the box’ and ‘outside the box’ are correct. They are both ways to talk about thinking a bit more creatively. You are much more likely to find the word ‘of’ used when you are listening to American English being spoken.

Both ‘outside the box’ and ‘outside the box’ can be used. However, the generally preferred term is ‘outside the box’. It is much more concise, which should always be the aim when speaking or writing.

These are both correct, so you can see how the addition of the ‘of’ really changes the sentence and the flow:

  • The manager asked the team to come up with new ideas. He wanted them to think outside the box.
  • The manager asked the team to come up with new ideas. He wanted them to think outside of the box.

Is It ‘Outside The House’ or ‘Outside of The House’?

You can use either ‘outside the house’ or ‘outside of the house’. However, the vast majority of people will prefer the former. It is a little bit easier to say. If you are speaking in American English, then you would likely say ‘outside the house’ instead.

Obviously, both of these sayings can be used to discuss something, or somebody, being outside of a house. There are no stipulations has to how far the thing has to be from the house. Hopefully, the following examples (both of which are correct) will show this:

  • The fire engine was outside the house on fire.
  • The event was being held outside of the house.

Is It ‘Outside The Room’ or ‘Outside of The Room’?

Both ‘outside the room’ and ‘outside of the room’ are grammatically correct. However, in most cases, you would want to use ‘outside the room’. This means dropping the ‘of’ preposition. It makes the sentence flow a little bit better.

As you can probably guess, these phrases both mean the same thing and they are 100% interchangeable. It doesn’t really matter which one you use although, once again, we do suggest that you try and stick to as few words as possible.

Here are ways that you can use both of these in a sentence:

  • The bike was located outside the room.
  • The child was sent outside of the room while the adults discussed something serious.

Is It ‘Outside The Door’ or ‘Outside of The Door’?

Both ‘outside the door’ and ‘outside of the door’ are correct. Americans are much more likely to say ‘outside of the door’, while the rest of the English-speaking world uses the other, but it doesn’t matter too much which one you use.

Here are examples of how they can both be used

  • The cat was waiting outside the door.
  • The parcel was left outside of the door.