IELTS grammar: Comparatives and Superlatives

Comparatives and superlatives are unusually high-stakes for a topic that sounds elementary, because Academic Task 1 is built almost entirely around comparison — describing which category is bigger, smaller, faster-growing, or most significant relative to the others in a chart or table — which means a candidate who mishandles this structure repeatedly is committing the same error many times across a single Task 1 response rather than once. The specific error pattern here isn't usually not knowing the rule; it's applying the wrong form to a specific adjective, confusing when a comparison needs "than" a different item versus needs "the" and a genuine three-way comparison, and failing to make comparisons precise enough to earn credit under Task Achievement for accurately describing data. Getting the mechanics right — which adjectives take "-er/-est" versus "more/most," when each structure is grammatically required, and how to quantify the size of a difference rather than just naming its direction — is one of the highest-return grammar topics specifically for Task 1, since so much of that task's content is comparative by nature.

The basic form rule splits adjectives by length and syllable count, and the exceptions matter as much as the rule itself. One-syllable adjectives take "-er" and "-est": "high, higher, highest"; "fast, faster, fastest." Two-syllable adjectives ending in "-y" change the "y" to "i" and take "-er/-est": "busy, busier, busiest"; "easy, easier, easiest." Most other two-syllable adjectives, and all adjectives of three or more syllables, use "more"/"most" instead of a suffix: "more careful," "most significant," "more expensive," "most impressive." A handful of common adjectives are genuinely irregular and simply have to be memorised rather than derived from the length rule: "good" becomes "better, best," "bad" becomes "worse, worst," and "far" becomes "farther/further, farthest/furthest." Mixing the two systems on a single word — "more higher," "most significantest," "more better" — is a basic error, but a genuinely persistent one, since candidates who have correctly learned "more significant" sometimes overcorrect by adding "-er" as well when writing under time pressure.

Comparatives require "than" when a comparison names two specific things being set against each other, and the object of the comparison needs to be genuinely comparable to the subject, not just present in the sentence: "The proportion of men who cycled to work was higher than that of women" correctly compares one proportion to another proportion, using "that of" to stand in for the repeated noun, rather than the ungrammatical "higher than women," which would compare a proportion directly to a group of people. This "that of" / "those of" substitution is one of the more reliable markers of higher-band Task 1 writing, precisely because it fixes a comparison that would otherwise be structurally sound but logically mismatched — comparing like with like is as much a content-accuracy issue as a grammar one, since "higher than women" is technically parseable but doesn't actually make the intended comparison.