Grammar · Commonly confused words · B1 · Intermediate
Affect vs Effect
Last updated 21 July 2026
In short
Affect vs effect at a glance
| Affect | Effect | |
|---|---|---|
| Word class | Verb — to affect | Noun — an effect / the effect |
| Meaning | To influence, change, or have an impact on something | A result, outcome, or consequence |
| Typical pattern | affect + object: rising prices affect households | have an effect on + noun; the effect of X on Y |
| Article test | Never takes 'a/an/the' in front of it | Usually follows 'a/an/the': a positive effect |
| Quick swap test | Swap in 'influence' — if it still works, use affect | Swap in 'result' — if it still works, use effect |
| Rare exception | Affect as a noun in psychology: a flat affect | Effect as a verb meaning 'bring about': effect change |
What's the difference between affect and effect?
Affect and effect sound almost identical, but in nearly every sentence you write or say, affect is the verb and effect is the noun. Affect means to influence, change, or have an impact on something: 'Poor sleep affects memory.' Effect means the result of that influence: 'Poor sleep has a negative effect on memory.'
A popular memory trick is RAVEN: Remember, Affect is a Verb, Effect is a Noun. If you can attach it directly to a subject and object like a normal verb, it's affect; if you can put 'a', 'an', or 'the' in front of it, it's effect.
- Long commutes affect people's stress levels.(verb — affect + object)
- Long commutes have a noticeable effect on stress levels.(noun — effect follows 'a')
- Long commutes effect people's stress levels.(→ affect (verb needed))
How do you test which word you need?
Two quick tests solve almost every case. First, try replacing the word with 'influence' or 'change' — if the sentence still makes sense, you need affect. Second, check whether an article (a, an, the) or a possessive (its, their) sits directly in front of the word — that position always calls for the noun, effect.
These tests work because affect almost always behaves like an ordinary transitive verb, taking a direct object, while effect almost always behaves like an ordinary countable or uncountable noun.
- Caffeine can affect (= influence) how well you sleep.
- Caffeine can have a real effect on how well you sleep.('a' before the word signals the noun)
- Doctors are studying the affects of caffeine on sleep.('the' before it needs the noun → the effects)
Are there exceptions to the affect/effect rule?
Two rare exceptions exist, but you can safely avoid both in IELTS Speaking and Writing. Effect can be a formal verb meaning 'to bring about' or 'to cause to happen': 'The new manager effected several changes.' It always sounds official and is easily replaced by 'bring about' or 'make'.
Affect can also be a noun in psychology, meaning an observable emotional state: 'The patient showed a flat affect.' Unless you are writing about psychology specifically, you will never need this sense — for everyday and exam English, affect stays a verb and effect stays a noun.
- The reforms effected real change in the department.(formal verb sense — rare, avoid unless confident)
- The counsellor noted the client's affect during the session.(psychology noun — a specialist use)
Common mistakes with affect vs effect
Real learner errors, corrected and explained — the fastest way to stop repeating them.
The new policy will effect thousands of workers.
The new policy will affect thousands of workers.
The sentence needs a verb meaning 'influence', so it takes affect, not effect.
The medicine had a strong affect on her energy levels.
The medicine had a strong effect on her energy levels.
After 'a strong', the sentence needs a noun — effect, not the verb affect.
Pollution effects marine life in serious ways.
Pollution affects marine life in serious ways.
'Pollution' is the subject acting on 'marine life', so the verb affects is required.
Researchers are still studying the affects of climate change.
Researchers are still studying the effects of climate change.
'The' before the word signals a plural noun — effects — not the verb affects.
Affect vs Effect in IELTS
Grammatical Range and Accuracy is 25% of your Speaking and Writing scores — here is where this structure earns marks.
Speaking
- Use affect as a verb when explaining causes in Part 3: 'Rising costs affect people's spending habits.' A Band 7 answer varies its verbs instead of repeating 'change' or 'influence' every time.
- 'Have a positive/negative effect on' is a flexible fixed phrase — dropping it into an answer signals natural range: 'Working night shifts has had a negative effect on my sleep.'
Writing
- Task 2 cause-and-effect essays depend on this pair constantly: 'Social media affects teenagers' mental health' versus 'Social media has a damaging effect on mental health.' Confusing the two is one of the most common Band 5–6 grammar slips examiners flag.
- Open a body paragraph with 'The effects of X on Y are...' as a strong topic sentence: 'The effects of urbanisation on air quality are well documented.'
Practise affect vs effect now
Five quick questions with instant feedback — every answer explained. No sign-up needed.
Question 1 of 5
The drought had a devastating ___ (noun) on crop yields.
Want the full set? All 8 affect vs effect exercises →
Check this rule in your own writing
Reading a rule is step one; seeing it in your own sentences is what changes your band score.
Paste a paragraph into the free IELTS Grammar Checker — it flags every affect vs effect mistake, explains the rule, and estimates your Grammatical Range & Accuracy band.
Related lessons
Frequently asked questions
Is it 'affect' or 'effect' when something causes change?
Can 'effect' ever be a verb?
What does the RAVEN trick mean for affect and effect?
Is it spelled 'side effects' or 'side affects'?
Next step
Hear this grammar scored in a real mock exam
SpeakMetry's AI examiner runs a full IELTS Speaking test and its report lists every grammar slip you made — with corrections. Your mistakes become your study plan.
Try the AI speaking exam