Affect and effect sound almost the same, and the spelling difference is one letter. The job they do in a sentence is completely different: affect is normally a verb, and effect is normally a noun.
If you can see the word as an action, use affect: "The weather affected the game." If you can see it as a result with the or an in front of it, use effect: "The effect of the weather was clear."
This page gives the meaning of each word, the quick test that separates them, and 15 sentences to practise. Every answer comes with a short reason, so the drill teaches the rule and not just the key.
What each word means
affect
affect (verb): to change or influence someone or something. The stress falls on the second syllable: uh-FECT.
effect
effect (noun): the result or change that something causes. It also has the stress on the second syllable: ih-FECT.
The rule
Affect is the action word
- Affect needs a subject and an object: "The rain affected the roads." Something does the affecting.
- After can, will, may or to, the base form is affect: "Money will not affect my choice."
- The past tense is affected and the -ing form is affecting.
- A formal use means "to pretend to feel": "She affected surprise at the news." You will rarely need it.
Effect is the result word
- Effect takes an article or an adjective in front of it: an effect, the effect, a strong effect.
- The usual pattern is the effect of something, or the effect on someone: "the effect of the drug on patients".
- Effects in the plural is very common: side effects, special effects, after-effects.
- Effect can also be a formal verb meaning "to make something happen": "The manager effected several changes." The everyday verb is affect.
The quick test
- Can you put the or an in front of the word? Then you need effect, the noun.
- Can you put to in front of it? Then you need affect, the verb.
- Can you replace the word with result? Then it is effect. Can you replace it with influence? Then it is affect.
- After an adjective such as strong, mild, negative or positive, use effect. Adjectives describe nouns.
Spelling and lookalikes
- Affect starts with an a, like action. Effect starts with an e, like end result.
- The noun affect exists in psychology and means the emotion a person shows. It is pronounced AF-ect and is rare outside medical texts.
- Do not confuse effect with effective, effectively or effectiveness. Those are related words, not the same word.
- Check the word that follows: if it is of, on or a plural verb, effect is likely. If it is a person or a thing being changed, affect is likely.
How to remember
The trick: A is for action (affect) and E is for end result (effect). If a or an fits before the word, the answer is effect.
Examples
- The weather affected our plans for the weekend.Affected is a verb, so the word is affect.
- The effect of the storm was clear by morning.The article the signals a noun, so the word is effect.
- Smoking affects your lungs and your heart.Affects is the present-tense verb with a third-person subject.
- The new law had an immediate effect on prices.An effect is a noun phrase; an comes before the noun.
- Her words affected me deeply.Affected is the past-tense verb.
- The medicine has few side effects.Side effects is a compound noun, so effect takes the plural -s.
- Nothing you say will affect my decision.After will, the base verb affect is correct.
- The film is famous for its amazing special effects.Special effects is a fixed noun phrase.
Common mistakes
- Wrong: The rain had a big affect on us. Right: The rain had a big effect on us.
- The article a points to a noun, and the noun is effect.
- Wrong: The medicine effected him badly. Right: The medicine affected him badly.
- The sentence needs the verb meaning to influence, which is affect.
- Wrong: The affect of the change was small. Right: The effect of the change was small.
- The effect of something is a noun phrase, so it takes effect.
- Wrong: Money does not effect happiness. Right: Money does not affect happiness.
- After does not, the base verb is needed, and the verb is affect.
- Wrong: The new policy had little affect. Right: The new policy had little effect.
- Little comes before a noun here, and the noun is effect.
Practice drill
Answer all 15 questions. Each answer is marked at once, and the rule is explained under the question.
The noise ___ my sleep last night.
Show answer and explanation
Answer: A. affected The sentence needs a past-tense verb, and the verb meaning to influence is affect.
The ___ of the noise was terrible.
Show answer and explanation
Answer: B. effect The article the comes before a noun, so the noun effect is correct.
Stress can ___ your appetite.
Show answer and explanation
Answer: C. affect After the modal can, the base verb affect is needed: stress can affect appetite.
The new rules had no ___ on us.
Show answer and explanation
Answer: D. effect No effect is a noun phrase, and effect is the result noun.
The film's special ___ were amazing.
Show answer and explanation
Answer: A. effects Special effects is a fixed noun phrase, so the plural effects is correct.
Her speech ___ everyone in the room.
Show answer and explanation
Answer: B. affected The past tense verb affected means influenced, which fits the sentence.
The medicine can ___ your mood.
Show answer and explanation
Answer: C. affect After the modal can, the base verb affect is needed, not the noun effect.
We studied cause and ___ in science class.
Show answer and explanation
Answer: D. effect Cause and effect is a fixed noun phrase, so the noun effect is correct.
The change did not ___ the final score.
Show answer and explanation
Answer: A. affect After did not, the base verb affect is needed to mean influence.
The ___ of the drought lasted for years.
Show answer and explanation
Answer: B. effect The article the signals a noun, and the result noun is effect.
Cold weather ___ my joint pain.
Show answer and explanation
Answer: C. affects The subject cold weather takes the present-tense verb affects.
The new manager ___ big changes in the office.
Show answer and explanation
Answer: D. effected Here effected is the formal verb meaning brought about, so the changes happened.
One ___ of the new policy was shorter meetings.
Show answer and explanation
Answer: A. effect One effect is a noun phrase, and effect means a result.
Nothing will ___ my decision.
Show answer and explanation
Answer: B. affect After will, the base verb affect is correct: nothing will influence my decision.
The pills had some side ___.
Show answer and explanation
Answer: C. effects Side effects is a fixed plural noun phrase, so effects is correct.
Questions learners ask
Is effect ever a verb?
Yes, but only in formal writing. To effect a change means to make the change happen: "The new director effected major reforms." In everyday English, affect is the verb and effect is the noun. Use affect unless you are sure about the formal pattern.
Is affect ever a noun?
Yes, in psychology and medicine. A person's affect is the emotion they show on their face and in their voice. It is pronounced AF-ect, with the stress on the first syllable, and it is rare outside clinical texts.
What is the fastest way to choose the right one?
Try to put a or an before the word. "A effect" sounds wrong but shows the pattern: articles go before nouns, so the word must be effect. If to or will fits before it instead, the word is affect, because those words introduce verbs.
More confusing words
Borrow vs lend
Borrow means you receive and give back. Lend means you give and get back. The preposition from and the person after the verb tell you which one to use.
Fewer vs less
Fewer goes with plural countable nouns, like fewer cars. Less goes with uncountable nouns and measurements, like less traffic.
Lose vs loose
Lose is a verb: to stop having something, or to not win. Loose is an adjective: not tight and not fixed.
Browse all the confusing word pairs or take the free A1 to C2 level test to find your starting point.