Compare - Affect or Effect

'Affect' and 'effect' are among the easiest words in the English language to mix up in both speech and writing, because they sound so similar and are sometimes used in similar ways. Here is a helpful guide to help you avoid this confusion.


'Affect' is usually a verb, meaning to impact, change, or cause to happen. A good way of remembering this is to imagine that the 'a' in 'affect' stands for 'action', so it must be a verb.

For example:

  • Jack has not been himself since his wife died. It has affected him deeply.

In the above sentence, we can see that Jack is not his usual self. The death of his wife has both changed him and had a significant emotional impact on him. The use of 'affected' expresses that.

Further examples:

  • If you really want to go and get a degree, don't let financial worries affect your decision.
  • The collapse of the business affected everyone badly, from staff to the local community.

Generally speaking, if you can substitute 'affect' with another verb and still keep your intended meaning, then you know you have used it correctly.

For example:

  • The plight of the refugees deeply affected Kate. CORRECT
  • The plight of the refugees deeply moved Kate. CORRECT

  • The recession affected our sales numbers. CORRECT
  • The recession harmed our sales numbers. CORRECT


'Effect' is usually a noun, and describes the result or consequence of a change or something being done. As it is often used when the end result of something is being discussed, a good way of remembering its correct usage is to imagine that the first letter ('e'), stands for 'end result'.

For example:

  • The beneficial effects of diet and exercise are well known.
  • The cold weather had a negative effect on my mood.
  • The medication had a positive effect on the patient.

In all of the above sentences, 'effect' is a noun, and is used as a synonym of 'result' or 'consequence'. It is a general rule that if you can substitute 'effect' for 'result' and still keep your intended meaning, then you are using it correctly.

For example:

  • A bad hangover was the effect of his night out with friends. CORRECT
  • A bad hangover was the result of his night out with friends. CORRECT

  • Sunburn was the effect of her spending the day at the beach. CORRECT
  • Sunburn was the result of her spending all day at the beach. CORRECT

While almost always a noun, 'effect' can sometimes be used as a verb in the sense of bringing something about or accomplishing something. However, in that context it tends to be used in a particularly formal manner rather than in everyday conversation.

For example:

  • Despite her promises, the politician's policies did little to effect change.

So, in summary, something must 'affect' something to produce an 'effect'. In other words, if something 'affects' you, you will feel the 'effect' of the change or impact it makes.

For example:

  • The new proposals will affect that department. (That department will be impacted or changed by the proposals)
  • That department felt the effects of the new proposals. (The department felt the results of the new proposals)

  • The cold weather really affected Susan's health. (The cold weather impacted or changed Susan's health)
  • The effect of the cold weather was that Susan got hypothermia. (The result of the cold weather was that Susan got hypothermia)

To avoid mistakes, keep in mind whether you are expressing action or talking about an event that has caused change. Here is an example of both words being used correctly in a sentence:

  • John's decision to close his business affected everyone. The whole community is feeling the effects.

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