Affect vs. Effect
“Affect” is most commonly a verb meaning to influence or cause change, while “effect” is most commonly a noun meaning a result. Both words have less common uses, so the part of speech is the safest first check.
Use “affect” most often as a verb meaning to influence or change something. Use “effect” most often as a noun meaning a result or consequence. Less common noun and verb senses exist, so do not rely on the shortcut in every technical or formal context.
Key details
Choose the right form
| Common job | Use | Meaning |
|---|---|---|
| Verb | affect | Influence or change something. |
| Noun | effect | A result or consequence. |
| Less common formal verb | effect | Bring about or cause something to happen. |
| Specialist noun | affect | A technical psychology sense exists; do not force the everyday shortcut onto specialist writing. |
Quick tests
Everyday verb-or-result test
Do you mean the action “influence,” rather than the result?
If yes: Use “affect.”
If no: If you mean a result or consequence, use the noun “effect.”
Caveat: The common shortcut covers ordinary usage but not every technical/formal sense; verify the sentence’s grammar and meaning.
Examples
The delay affected the launch date.
“Affect” is the verb meaning influence.
The delay had a measurable effect on sales.
“Effect” is the noun meaning result.
The delay had an affect on sales.
Better: The delay had an effect on sales.
In ordinary usage the result noun is “effect.”
Further guidance
Core difference
The everyday distinction is grammatical: affect is usually the action and effect is usually the result. “The weather affected the match” uses the verb; “The weather had an effect on the match” uses the noun.
Exceptions
English has additional senses. “Effect” can be a verb meaning to bring something about, and “affect” can be a noun in specialist psychology contexts. Those uses are real but much less common than the everyday verb/noun pattern.
Fast Test
If you mean “influence,” try affect. If you mean “result,” try effect. Then check whether the sentence needs a verb or a noun.
Sentence Patterns
The verb “affect” normally takes its object directly: “The change affected everyone.” The noun “effect” commonly appears in constructions such as “an effect on” something.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- Affect or effect? — Cambridge Grammar (opens in a new tab)Cambridge University Press · Core affect/effect distinction
- Word patterns: affect someone or something — Cambridge Grammar (opens in a new tab)Cambridge University Press · Affect/effect construction patterns