Affect or Effect?

The Quick Answer
What is the difference between "effect" and "affect"?
  • Effect. "Effect" is a noun. "Effect" means result, consequence, or appearance.
  • To Affect. "To affect" is a verb. "To affect" means to transform or to change.
Got it? Take a quick test.

Infographic for "Affect" and "Effect"

This infographic outlines the main difference between "to affect" and "effect."

affect or effect?

Click on the Two Correct Sentences
(Interactive Game)

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Affect and Effect

There is often confusion over the words "effect" and "affect." In order to understand which to use, you must know the difference between a noun and a verb.

"Effect" is a noun. "Affect" is a verb. (If you're not confident with spotting nouns and verbs, there are some workarounds below to help.)

Effect

"Effect" is a noun meaning result, outcome, consequence, or appearance. For example:
  • What effect did your reprimand have?
  • That is a nice effect.

Affect

"To affect" is a verb meaning to impact on, to transform, or to change. For example:
  • Did the cold affect you?
  • Do not use low-fat milk. It will affect the taste.

It's Not That Simple Unfortunately

Most of this page is dedicated to telling you that "effect" is a noun and "affect" is a verb. That is an appropriate start point for learning about the difference between "effect" and "affect," but unfortunately it is not always true. Be aware that "effect" can be a verb, and "affect" can be a noun.

The Verb "To Effect"

"To effect" as a verb is fairly rare, but it is useful in business writing. It means to bring into being. For example:
  • We will effect the new law on Monday.
  • The new policy will be effected as soon as the paper is signed.

The Noun "Affect"

The noun "affect" is extremely rare. It is used in psychology to describe a subjective feeling caused by a thought or other stimulus. It is similar to mood or emotion and carries a connotation of there being external physical signs.  For example:
  • The patient displayed an unusual affect when questioned.

A Video Summary

Here is a short video summarizing the difference between affect and effect.

This Top Tip Will Work Most of the Time

You almost certainly want effect (not affect) if the word before is an or the.

A Little Trick To Spot "Effect"

The word "effect" has several meanings. It can mean outcome, consequence, or appearance. Try using one of these instead of "effect." If the sentence still makes sense, then "effect" is almost certainly correct.

(This trick works because "effect" is a noun, just like the words outcome, consequence, and appearance.)

A Little Trick To Spot "Affect"

Try using the verb to transform (in its various forms, e.g., transforming, transformed, transforms) instead of "affect." If the sentence still makes sense, then "affect" is almost certainly correct. However, if you find yourself trying to use transformation, then you should be using "effect" because both are nouns.

(This trick works because to transform is a verb, just like to affect. )

Example Sentences with "Effect" and "Affect"

Here are some example sentences with "effect" and "affect":

Example 1:
  • What effect did foot-and-mouth disease have on your business?
    • (The word effect is a noun.)
Top Tip

Try substituting the noun "effect" with the noun consequence to confirm that it's a noun.

Substitution Test: "What consequence did foot-and-mouth disease have on your business?"
(As this sounds okay, effect must be correct.)
Example 2:
  • Did foot-and-mouth disease affect your business?
    • (The word affect is a verb.)
Top Tip

Try substituting the verb affect with the verb transform to confirm that it's a verb.

Substitution Test: "Did foot-and-mouth disease transform your business?"
(As this sounds okay, affect must be correct.)
Example 3:
  • Do not allow this incident to effect your decision.
Top Tip

Do the substitution test.

Substitution Test: "Do not allow this incident to consequence your decision."
(As this is nonsense, effect must be wrong.)

The Other Substitution Test: "Do not allow this incident to transform your decision."
(As this sounds okay, affect must be correct.)
Note: Sometimes, the noun-substitution test won't work with consequence because effect is quite a versatile word. You might have to try other nouns, e.g., appearance. If you find yourself trying to use this word as a verb (e.g., appear, appears), then you should be using affect not effect.

"Affecting" and "Affected"

Affecting and affected are spelt with an "a" more than 99% of the time. The words "effecting" and "effected" are extremely rare. If you can substitute "transforming" or "transformed," then you definitely want the "a" version. If (and it's a big if) you can substitute "being brought into force" or "brought into force," then you want the "e" version - I bet you don't though!
Interactive Exercise
Here are three randomly selected questions from a larger exercise, which can be edited and printed to create exercise worksheets.

See Also

adverse or averse? appraise or apprise? avenge or revenge? bare or bear? complement or compliment? dependant or dependent? discreet or discrete? disinterested or uninterested? e.g. or i.e.? envy or jealousy? imply or infer? its or it's? material or materiel? poisonous or venomous? practice or practise? principal or principle? tenant or tenet? who's or whose? advice or advise?
What are nouns? What are verbs? List of easily confused words