Comparison and degree
Comparison relates entities or measurements by degree, equality or difference and requires control of adjective form and comparison structure.
01 · Concept foundation
Understand the terms before applying the rule
Each term below names a different grammatical object. Open examples and compare their function rather than memorising a Vietnamese translation alone.
comparative/kəmˈpærətɪv/
dạng so sánh hơnA form or construction expressing a higher, lower or different degree between entities.
higher than; more reliable than
cao hơn; đáng tin cậy hơn
superlative/suːˈpɜːlətɪv/
dạng so sánh nhấtA form identifying the highest or lowest degree within a defined set.
the highest value
giá trị cao nhất
degree modifier/dɪˈɡriː ˈmɒdɪfaɪə/
từ bổ nghĩa mức độAn adverb modifying the strength or size of a comparison.
slightly higher; considerably more stable
cao hơn một chút; ổn định hơn đáng kể
Complete lesson scope
Do not stop at one formula
Comparative and superlative morphology
As ... as, less, least and equality/inequality
Degree modifiers: much, far, slightly, by far
Double comparatives, proportional change and repeated comparison
Decision boundary: The comparison target must be grammatically and logically parallel to the item being compared.
02 · Controlling rule
A valid comparison requires comparable entities, a stated or recoverable dimension and the correct morphological or analytic form. Degree modifiers, ratio expressions and comparison complements change the mathematical and rhetorical meaning.
as + adjective/adverb + as | comparative + than | less/fewer + noun + than | the + superlative + in/of | n times as + adjective + as | the + comparative..., the + comparative...Comparison and degree: equality, difference, ranking and proportional change
Build logically parallel comparisons, choose the correct comparative or superlative form, calibrate the size of a difference and describe dynamic relationships precisely in conversation and IELTS.
A comparison is valid only when the compared items, property and reference set are all explicit or recoverable.
Comparative grammar encodes a relation, not simply a stronger adjective. Higher than requires a comparison target; the highest requires a defined set. In data writing, by 20% and to 120 provide different numerical relations and must not be confused.
What exactly are the two compared items, and are they grammatically parallel?
Is the relation equality, superiority, inferiority, ranking or proportional change?
Does the adjective take -er/-est, more/most or an irregular form?
How large is the difference, and what evidence supports the degree modifier?
1. Comparative and superlative formation
Short adjectives commonly take -er/-est; longer adjectives commonly take more/most. Irregular forms and spelling changes must be controlled lexically.
short adjective + -er/-est · more/most + longer adjective · irregular: better/best, worse/worstOne-syllable adjectives usually take -er/-est: high, higher, highest; double a final consonant after short vowel: big, bigger, biggest.
Many two-syllable adjectives in -y take -ier/-iest: easy, easier, easiest; others vary by usage.
Do not combine two comparative markers: better, not more better; more reliable, not reliabler.
The revised mesh is finer and more stable than the original mesh.
The revised mesh is finer and more stable than the original mesh.
Fine takes -er; stable normally uses more. Both properties share the same comparison target.
Neutral technical comparison.Scenario C produced the worst agreement with the observed peak.
Scenario C produced the worst agreement with the observed peak.
Worst is the irregular superlative of bad and requires a defined comparison set supplied by the scenarios.
Comparative
subject + be/verb + comparative (+ degree modifier) + than + parallel targetCompare two entities, groups, values or situations.
higher than
more reliable than
less expensive than
fewer errors than
- Use less with degree/amount and fewer with plural count nouns.
Equality and inequality
as + adjective/adverb + as · not as/so + adjective/adverb + asState equal or lower degree relative to a target.
as accurate as
not as stable as
twice as large as
- Use object pronouns in informal speech and full clauses in careful writing when needed: as I do, not as me, for explicit clause comparison.
Superlative and rank
the + superlative + noun + in/of + comparison setIdentify an extreme or ranked member within a defined set.
the highest value in the series
one of the most reliable methods
the third largest port
- The set must contain at least three members for ordinary superlative ranking.
Proportional relationship
the + comparative + clause, the + comparative + clauseExpress coordinated change between two variables.
The higher the tide rises, the farther salt water travels inland.
- This grammar shows association; add evidence before claiming causation.
less versus fewer
The method used less memory.
Memory is an amount/mass in this sense.
The method produced fewer errors.
Errors are countable units.
Use less for amount/degree and fewer for plural count nouns in formal edited English.
increase by versus increase to
The value increased by 20%, from 100 to 120.
By states the amount of change.
The value increased to 120.
To states the final level.
Do not use by for the endpoint or to for the difference.
logical parallelism
The population of City A is larger than City B.
Faulty: population is compared with a city.
The population of City A is larger than that of City B.
Correct: population is compared with population.
Restore the omitted noun mentally; if the two categories differ, use that of/those of or rewrite fully.
Everyday conversation and IELTS Speaking
- Prefer
- Use simple contrasts with reasons: X is more convenient than Y because...; X is not as practical as Y when...
- Avoid
- Long stacked comparisons with no clear target or reason.
- Why
- Speaking rewards clear development more than ornamental complexity.
IELTS Writing Task 1
- Prefer
- Use precise comparative trends, degree modifiers and rank: slightly higher, by far the largest, twice as high as, rose by/to.
- Avoid
- Unsupported strong modifiers and ambiguous ratios such as three times higher.
- Why
- Task 1 requires faithful numerical relationships, not rhetorical exaggeration.
Academic and technical writing
- Prefer
- Use parallel categories, explicit baselines and cautious proportional language.
- Avoid
- Comparing a measured property with an entity, or treating correlation as causation.
- Why
- Scientific comparison must be reproducible and logically interpretable.
Formation and irregular forms
Usage can vary for some two-syllable adjectives; use a reliable dictionary when uncertain.
| Base | Comparative | Superlative |
|---|---|---|
| high | higher | highest |
| easy | easier | easiest |
| reliable | more reliable | most reliable |
| good/well | better | best |
| bad/badly | worse | worst |
| far | farther/further | farthest/furthest |
Degree modifiers
Choose a modifier only when the evidence supports its magnitude.
| Small difference | Large difference | Superlative emphasis |
|---|---|---|
| slightly, marginally, a little, somewhat | much, far, considerably, substantially, significantly | by far, easily, one of the |
High-value IELTS comparison patterns
Use the pattern that matches the mathematical relation.
| Purpose | Pattern | Example |
|---|---|---|
| difference | X was N units higher than Y | The peak was 0.4 m higher than the baseline. |
| ratio | X was twice as high as Y | The 2025 rate was twice as high as the 2015 rate. |
| rank | X had the second highest value | Region B had the second highest value. |
| covariation | The more X..., the more Y... | The longer the storm lasted, the greater the erosion became. |
✕ The revised model is more better than the original.
✓ The revised model is better than the original.
Better already carries comparative meaning; do not add more.
✕ The second value was very higher.
✓ The second value was much higher.
Very normally modifies a base adjective, not a comparative; use much/far/slightly according to size.
✕ The salary of engineers is higher than teachers.
✓ The salary of engineers is higher than that of teachers.
Salary must be compared with salary, not with people.
✕ This was highest value in the series.
✓ This was the highest value in the series.
A standard attributive superlative within a defined set normally takes the.
✕ The rate was twice higher than in 2020.
✓ The rate was twice as high as in 2020.
Twice as high as gives an unambiguous 2:1 ratio.
Choose by meaning, countability and discourse role
1. Which sentence contains a logically parallel comparison?
2. Which expression gives an exact 2:1 ratio most clearly?
3. Choose the correct description of a small difference.
4. What does the more accurate the input, the more reliable the output express?
Write a six-sentence IELTS Task 1 comparison using: one equality, one small comparative difference, one large comparative difference, one exact ratio, one ranked superlative and one by/to change statement.
Every comparison has a clear and parallel target.
Comparative and superlative forms are morphologically correct.
Degree modifiers match the actual size of the difference.
Ratios, differences and endpoints are not confused.
Superlatives specify a meaningful comparison set.
03 · Worked examples
Observe form, function and meaning together
The offshore station recorded a water level 0.35 metres higher than that of the estuary station.
Trạm ngoài khơi ghi nhận mực nước cao hơn trạm cửa sông 0,35 mét.
Scenario B produced twice as much inundated area as Scenario A.
Kịch bản B tạo diện tích ngập lớn gấp đôi kịch bản A.
The faster the wind speed increases, the more rapidly the storm surge develops.
Tốc độ gió tăng càng nhanh thì nước dâng do bão phát triển càng nhanh.
04 · High-risk contrast
Explain why one form fails, not only which answer is correct
The second estimate was more better and twice higher than the first.
The second estimate was better and twice as high as the first.
Better already contains comparative meaning, so more is redundant. For an exact 2:1 ratio, twice as high as is clearer than twice higher than, which may be interpreted inconsistently.
05 · Mastery check
Apply the rule before marking the lesson complete
Which sentence is grammatically acceptable in the target system?
Which description best defines “comparative”?
Which example is one of the verified target patterns in this lesson?
Which structural formula belongs to this lesson?
Complete all four checks, then submit a sentence for target-form feedback.
06 · IELTS Academic
Transfer grammar into a real communicative task
Task 1 depends heavily on accurate comparisons: higher/lower than, similar to, respectively, by versus to, twice as many and the largest proportion. Task 2 and Speaking use comparisons to rank priorities and qualify opinions, for example public transport is considerably more efficient than private car use in dense cities.
Form regular, irregular and analytic comparatives and superlatives accurately.
Distinguish an absolute difference, a percentage change and an exact ratio.
Compare like with like using that of/those of or controlled ellipsis where needed.