/səbˈstæn.ʃəl/ · adjective
substantial
đáng kể — lớn đến mức có ý nghĩa về số lượng, giá trị hoặc tầm quan trọng.
The upgrade in 5 seconds
a big increase in spending
a substantial increase in public spending
No definition. No dictionary. Just the sentence, made better.
Section 02
The Common Mistake
Many IELTS candidates lean on big, large and a lot of.
These words are correct — but “big” is vague and slightly informal. An examiner reads it as a ceiling on your Lexical Resource.
“Yes — that's exactly how I write, too.”
Section 03
The Better Choice
This is the step from Band 6 to Band 7 — not a harder word, a more precise one.
Section 04
Why It Works
“Big” tells the examiner something is large. “Substantial” tells them it is large enough to matter — significant in size, value or effect.
That precision is why academic writers prefer it. It pairs naturally with abstract, measurable nouns (amount, increase, evidence, improvement, proportion) — exactly the collocations Band 8 rewards.
Section 05 · The core of the lesson
Upgrade Matrix
Watch one idea climb from Band 6 to Band 9 — same meaning, rising precision.
Many countries spend a big amount of money on education.
Correct, but “big amount of money” is vague and wordy.
Many countries spend a substantial amount of money on education.
Better adjective, but “amount of money” still drags.
Many governments allocate substantial funding to education.
Tighter noun + a concrete agent. This is the target.
Many governments allocate substantial public funding to education, treating it as a long-term investment.
Developed, specific, and fully controlled.
There was a big rise in unemployment.
Fine, but flat and imprecise.
There was a substantial rise in unemployment.
“Substantial rise” is a strong, measurable collocation.
The period saw a substantial rise in unemployment, particularly among young graduates.
Precise, quantified, and specific — nothing wasted.
Section 06 · Read against the band descriptors
Examiner's Insight
How this word measures up against the public IELTS Writing & Speaking band descriptors — an editorial read, not a real examiner's verdict.
In Writing Task 1 and Task 2, “a substantial increase” is the kind of phrasing the band descriptors reward — not because the word is rare, but because it is precise and measurable. It signals control of academic register, not just a bigger vocabulary.
Section 07
Native Radar
Not about grammar — about whether a native speaker would actually say it.
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Native would naturally say
a substantial improvement in living standards
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Native might say
a substantial meal
Correct, but here it means “large and filling” — everyday, not academic.
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Native almost never says
a substantial difference of two cents
Substantial means large, so it clashes with tiny amounts.
Section 08 · Under 5 minutes
Active Recall
01 Rewrite using substantial: “There was a big improvement in test scores.”
Model answer
There was a substantial improvement in test scores.
02 Choose the stronger collocation: substantial happiness / substantial evidence.
Answer
substantial evidence — precise and academic.
03 Complete naturally: “The new policy led to a ______ reduction in traffic.”
Answer
substantial — “a substantial reduction” is a perfect pairing.
Substantial means large enough to matter —
not just big.
If you forget everything else, keep this.
Section 10 · Editorial rating
Examiner Score
Section 11 · The editor closes
Final Verdict
Substantial is one of the most reliable adjectives in academic English. It isn't a word you show off — it's one you lean on whenever “big” feels too loose. The moment you write “a substantial increase” instead of “a big increase,” your writing sounds measured and precise.
Learn it once, pair it with the right nouns — amount, increase, evidence, improvement — and it will earn its place in almost every essay and chart description you write.
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