Affect or Effect | Difference & Example Sentences

Published on 21 July 2022 by Eoghan Ryan. Revised on 23 August 2023.

Affect and effect are two related words that are commonly confused. They’re pronounced similarly, and in their most common meanings they both refer to change, but they have different grammatical roles:

Affect is a verb that describes the act of producing a change in someone or something.

Effect is a noun that refers to the result or change itself, as in the phrase ’cause and effect’.

Examples: ‘Affect’ in a sentence	Examples: ‘Effect’ in a sentence
Staying up late tonight might affect your performance tomorrow.	Tourism has had a positive effect on the economy.
The result of the exam will affect your overall grade.	The fog created an eerie effect.
The independent variable affects the dependent variable.	The drug’s side effects are unknown.

Note

It’s also possible to use effect as a verb and affect as a noun, but they have different meanings and are much less commonly used than the definitions above.

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‘Affect’ is typically a verb
‘Effect’ is typically a noun
‘Effect’ as a verb
‘Affect’ as a noun
‘Affect’ to mean ‘pretend’
Worksheet: Effect or affect
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‘Affect’ is typically a verb

As a transitive verb, affect is always used with an object. So you’ll always include the name of the person or thing being affected.

Example: ‘Affect’ as a verb

The speed of the reaction was affected by the temperature.

Tip

If you’re unsure whether you’re using affect correctly, substitute it with another verb (e.g., transform, modify, change).

If the sentence still makes sense, affect is the correct word to use.
If not, you probably mean effect.

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‘Effect’ is typically a noun

Effect is a noun meaning the result or consequence of a cause or action. It is often used along with an adjective (e.g., positive, negative, unexpected).

Example: ‘Effect’ as a noun

The quality of the food has a major effect on the taste.

Effect is used for some expressions like ‘take effect’ and ‘in effect’. It’s also related to the adjective ‘effective’.

Tip

If you’re unsure whether you’re using effect correctly, substitute it with another noun (e.g., outcome, result, consequence).

If the sentence still makes sense, effect is the correct word to use.
If not, you probably mean affect.

‘Effect’ as a verb

When used as a verb, effect means ’cause something to come into being’. It’s frequently followed by the word ‘change’.

Example: ‘Effect’ as a verb

The civil rights group effected change through peaceful protest.

‘Affect’ as a noun

When used as a noun, affect can refer to a visible emotional response. In this meaning, it’s pronounced with the first syllable stressed: [aff-ect].

Example: ‘Affect’ as a noun

The patient’s facial affect indicated she may have been distressed by the conversation.

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‘Affect’ to mean ‘pretend’

Affect can also be used (again as a verb) to describe someone pretending, or behaving in a way that is insincere, faked, or unnatural.

Example: ‘Affect’ to mean ‘pretend’

Though he was offended, he affected a smile.

She affected a French accent.

Worksheet: Effect or affect

You can test your understanding of the difference between ‘affect’ and ‘effect’ with the worksheet below. Fill in a version of ‘affect’ or ‘effect’ in each sentence.

The weather might ______ our plan to go camping.
This paper examines the ______ of global warming.
Caffeine doesn’t ______ him.
The scenery has a calming ______.
If you want to ______ change, the first step is to raise awareness of the problem.
He ______ an angry tone of voice.

The weather might affect our plan to go camping.
- Here, ‘affect’ is correct, as you’re referring to the act of producing a change.

This paper examines the effects of global warming.
- Here, ‘effect’ is correct, because you’re describing the results of something. The plural of ‘effect’ is ‘effects’.

Caffeine doesn’t affect him.
- ‘Affect’ is a transitive verb, so it will always be used with an object. In this instance, the object is ‘him’.

The scenery has a calming effect.
- ‘Effect’ is often used along with an adjective (e.g., positive, negative, unexpected). In this instance, the adjective is ‘calming’.

If you want to effect change, the first step is to raise awareness of the problem.
- ‘Effect’ can sometimes be used as a verb meaning ’cause something to come into being’. It’s frequently followed by the word ‘change’.

He affected/affects an angry tone of voice.
- ‘Affect’ can be used to describe behavior that is faked or insincere. The past simple form of ‘affect’ is ‘affected’; the present form ‘affects’ would also fit here.

Eoghan Ryan

Eoghan has a lot of experience with theses and dissertations at bachelor's, MA, and PhD level. He has taught university English courses, helping students to improve their research and writing.