Decline, Decrease, and Deplete: What’s the Difference? - Bluejay English

English learners often struggle to choose the right word when talking about things becoming smaller or fewer. 

Words like decline, decrease, and deplete all describe forms of reduction, but they aren't used in the same way. In this post, we'll break down their meanings, show how they’re used in real-life examples, and help you avoid common mistakes.

1. Decline

Used when talking about a gradual reduction over time, especially in number, importance, or quality.

                                                                                               Source: GIPHY, 2014

Typical Use Cases:

• Population trends
• Health conditions
• Popularity or frequency of something

Examples:  

• The number of staff has declined from 217,000 to 114,000. 
• Handwritten letters have declined with the rise of digital communication. 
• Her health began to decline after the surgery.

💡Tip: 'Decline' often implies a slow, continuous drop over time.

2. Decrease

Used when referring to a reduction in amount, size, or intensity. More neutral and general than 'decline.' 

                                                                               Source: Kochstrasse, 2019

Typical Use Cases:

• Weather/ temperature
• Noise or pollution
• Costs or prices

Examples:

• The temperature is expected to decrease by 10 degrees tonight. 
• The noise from the construction site decreased in the afternoon. 

💡Tip: 'Decrease' can be used as both a verb and a noun.

• There was a noticeable decrease in traffic. 

3. Deplete

Describes the use of something until it is almost gone. Often used with resources or supplies that are limited. 

                                                                                      Source: Fabian Molina, 2018

                                                                               

Typical Use Cases

• Natural resources (e.g. oil, water, fish stocks)
• Savings or energy
• Medical/ emergency supplies

Examples:

• Overfishing has severely depleted the fish population in the lake.
• Unexpected medical bills began to deplete our life savings. 

💡Tip: 'Deplete' emphasises exhaustion or running out of something.

🚩Try It Yourself

Which word fits better?

                           Korea's birth rate has _____ steadily over the past decade.

Drop your guess in the comments - I'll reveal the correct answer there! :)