Quick answer: Both decrease and reduce mean to become or make smaller. Decrease is typically intransitive (numbers decrease on their own) or transitive. Reduce is more actively transitive — you reduce something by taking deliberate action to make it smaller. For a fuller definition, see the Cambridge Dictionary entry for ‘decrease’.
Comparison Table
| Word | Grammar | Agency | Example |
|---|---|---|---|
| decrease | transitive or intransitive | can happen naturally | Sales decreased last year. |
| reduce | usually transitive | requires deliberate action | We reduced costs by 20%. |
Understanding Decrease
Decrease describes a quantity or level becoming smaller. It can be used intransitively, where the subject itself gets smaller with no direct object, or transitively, where an agent makes something smaller. It often describes statistical or measurable change.
The temperature decreased overnight.
Crime rates have decreased steadily.
The company decreased its workforce.
Profits decreased by 10% in Q3.
Decrease as a Noun
Decrease also works as a noun: “There was a significant decrease in demand.” Reduce does not share this noun form — you would say “a reduction” instead.
Understanding Reduce
Reduce almost always implies active intervention by a person, organisation, or policy. It typically takes a direct object, making it transitive. It is the natural choice when describing purposeful action to bring a figure down.
We need to reduce carbon emissions.
The government reduced the tax rate.
Exercise can help reduce blood pressure.
They reduced the price by half.
Common Mistakes
✗ We need to decrease carbon emissions. (not wrong, but decrease sounds more passive)
✓ We need to reduce carbon emissions. (emphasises deliberate effort)
✗ The numbers reduced last year. (unnatural; reduce needs an agent)
✓ The numbers decreased last year. or They reduced the numbers last year.
✗ There was a reduce in sales.
✓ There was a decrease/reduction in sales. (the noun of reduce is reduction)
Also compare: Increase vs Grow, Fall vs Drop, Develop vs Improve. Browse all confusing word pairs →
Quick Check: Decrease or Reduce?
Four questions — choose the correct word.
1. “Sales ___ by 15% over the winter.” (no agent mentioned)
2. “The government plans to ___ spending next year.”
3. “There was a sharp ___ in the number of applicants.” (noun)
4. “They ___ the price of the ticket by half.”
Frequently Asked Questions
What is the difference between decrease and reduce?
Decrease can happen naturally or be caused by an agent and can be used intransitively. Reduce implies deliberate action and almost always takes a direct object. Both describe something becoming smaller.
Can decrease be used intransitively?
Yes. “The temperature decreased overnight” has no agent performing the action. Reduce used intransitively sounds unnatural; you would say “the temperature dropped” rather than “the temperature reduced.”
Is there a noun form of reduce?
Yes — reduction. Decrease itself can be a noun: “a decrease in sales.” You would not say “a reduce”; you say “a reduction” or “a decrease.”
Are decrease and reduce interchangeable?
Often, but not always. When an agent actively brings something down, reduce is the stronger choice. When something simply gets smaller on its own, decrease fits better. In many sentences either works.
Which word is more common in academic writing?
Both are common in academic writing. Decrease often appears in data descriptions: “Values decreased significantly.” Reduce is preferred when describing interventions: “The treatment reduced symptoms.”
Can reduce be used intransitively?
In standard British and American English, reduce used without an object sounds unnatural: “Costs reduced” is rare compared to “Costs decreased” or “They reduced costs.” Prefer decrease or fall for intransitive use.
What is the opposite of decrease?
The opposite of decrease is increase. The opposite of reduce is typically increase or raise depending on context: “They raised prices” parallels “They reduced prices.”
Can I say “the noise reduced”?
It sounds awkward. Native speakers prefer “the noise decreased” or “the noise died down.” Use reduce with an agent: “The wall reduced the noise.”
How do decrease and reduce differ in cooking English?
In cooking, “reduce” is the technical term: “Reduce the sauce by half” (simmer until it thickens). You would not say “decrease the sauce.” This is a specific culinary use of reduce.
Which word should I use in IELTS writing?
Both are acceptable. For graphs and data, use decrease when describing natural trends: “The figure decreased.” For policy discussions, use reduce: “Governments should reduce emissions.”