How to Describe a Line Graph: Vocabulary for Trends (Increase, Decrease, Stable)

[IELTS-Community]

Accurately describing a line graph is a core requirement in IELTS Academic Writing Task 1. Examiners assess your ability to report data objectively, select precise vocabulary, and show clear comparisons over time. Many candidates struggle not because they misunderstand the graph, but because they rely on repetitive or inappropriate trend words. How can you describe changes clearly without sounding basic or exaggerated? The answer lies in using varied, accurate vocabulary for increase, decrease, and stability, supported by correct grammar.

This article explains essential trend vocabulary and shows how to apply it effectively in IELTS Task 1 responses.

Vocabulary for Upward Trends (Increase)​

When data moves upward, you must describe both direction and intensity. IELTS examiners reward accuracy more than dramatic language.

Common verbs for increase​

• Increase
• Rise
• Grow
• Climb
• Go up

Example:
The number of international students rose steadily between 2010 and 2015.

Strong verbs for sharp increases​

• Surge
• Soar
• Jump
• Rocket

Use these only when the graph shows a sudden or significant rise. Overuse weakens accuracy.

Example:
Online sales surged after 2020.

Nouns for upward movement​

• An increase
• A rise
• Growth
• An upward trend

Example:
There was a gradual increase in employment levels.

Adverbs to show speed and scale​

• Gradually
• Steadily
• Rapidly
• Dramatically

Combining verbs with adverbs improves precision and lexical range.
Example:
Energy consumption increased gradually over the decade.

Vocabulary for Downward Trends (Decrease)​

Describing decline requires the same level of care. Avoid using strong decline words unless the data justifies them.

Common verbs for decrease​

• Decrease
• Fall
• Drop
• Decline
• Go down

Example:
Car usage declined between 2008 and 2012.

Strong verbs for sharp decreases​

• Plummet
• Collapse
• Dip sharply

Example:
Factory output plummeted during the recession.

Nouns for downward movement

• A decrease
• A fall
• A reduction
• A downward trend

Example:
The chart shows a significant reduction in water usage.

Adverbs for the rate of decline​

• Slightly
• Gradually
• Sharply
• Significantly

Accurate pairing matters. A slow decline should never be described as sharp.

Vocabulary for Stable or Unchanging Trends​

Graphs often show periods of little or no change. Many candidates overlook this category, yet examiners expect it.

Verbs for stability​

• Remain stable
• Stay constant
• Level off
• Plateau

Example:
The figure remained stable at around 50 units.

Nouns and phrases for no change​

• Stability
• A constant level
• No significant change

Example:
After 2015, the trend reached a plateau.

Adverbs to support accuracy​

• Relatively
• Largely
• Almost

Example:
Prices remained relatively stable throughout the period.

Combining Trends in One Sentence​

High-band responses often compare trends within a single sentence. This shows control and cohesion.

Example:
While smartphone usage increased steadily, landline ownership declined sharply.
This structure highlights contrast and avoids repetition.

Grammar Patterns You Must Control​

Vocabulary alone does not guarantee accuracy. IELTS Task 1 requires correct grammatical patterns.

Verb-based structure​

The number of users increased from 10 million to 25 million.

Noun-based structure​

There was an increase from 10 million to 25 million users.

Prepositions to remember​

• Increase from … to
• Fall by
• Remain at

Incorrect prepositions reduce the Grammar score even when the vocabulary looks strong.

Common Mistakes to Avoid​

One frequent error involves describing minor changes with extreme verbs. Another consists in repeating the same verb throughout the report. Examiners notice repetition quickly, which limits the Lexical Resource band. Candidates should also avoid personal opinions, predictions, or explanations of causes unless the task explicitly asks for them.
Data description requires neutrality. You report what the graph shows, not why it happens.

Conclusion​

Describing a line graph in IELTS requires precise vocabulary for increases, decreases, and stable trends, supported by correct grammar and measured tone. Strong verbs, accurate adverbs, and varied sentence structures help communicate data clearly. When candidates match language strength to the data shown, coherence improves, and examiner confidence rises. Mastery of trend vocabulary turns a technical task into a scoring opportunity.