IGCSE Grade Boundaries Explained (2026): What Percentage Is an A*?
Every August, thousands of IGCSE students refresh the same question: "What percentage do I need for an A*?" — and every August, the honest answer surprises them. There is no fixed percentage. Grade boundaries move every session, and understanding why is the difference between panicking over a hard paper and knowing exactly how safe your grade really is. Here's how IGCSE grading actually works — and how to use it to your advantage.
- Grade boundaries (Cambridge calls them grade thresholds) are the minimum raw marks for each grade — and they're set after every exam session, not before.
- There's no fixed percentage for an A*. On extended papers it often lands somewhere around 80–90%, but a hard paper pushes boundaries down.
- On the 9–1 scale, 7 ≈ A, 4 ≈ C, 1 ≈ G — those anchors are fixed by design; an A* sits around grades 8–9.
- On Cambridge Core papers the maximum grade is a C — you cannot get an A* no matter your score.
- The winning mindset: train comfortably above your target boundary, so wherever it lands, you're clear of it.
What grade boundaries actually are
A grade boundary is the minimum raw mark you need for a given grade in a specific exam series. If the A* threshold for your Chemistry paper is 168/200 and you score 168, you get the A* — score 167 and you don't. Brutal, but transparent.
The part most students miss: boundaries are decided after everyone has sat the paper. Examiners look at how the whole cohort performed, compare the paper's difficulty against previous years, and then place the boundaries so that a grade means the same thing from one year to the next.
A*–G vs 9–1: what the grades mean
Cambridge IGCSE is graded A*–G, and many syllabuses are also offered on the 9–1 scale (Edexcel International GCSE is 9–1). The scales are deliberately anchored to each other:
| 9–1 grade | A*–G equivalent | What it signals |
|---|---|---|
| 9 | High A* | Top of the cohort — above a standard A* |
| 8 | A* / high A | The classic A* zone |
| 7 | A | Anchor point — bottom of 7 = bottom of A |
| 6 | High B | Strong pass |
| 5 | Low B / high C | "Strong pass" in UK terms |
| 4 | C | Anchor point — the standard pass |
| 3 | D / E | Below standard pass |
| 2 | E / F | |
| 1 | G | Anchor point |
So what percentage is an A*?
The honest answer: it depends on the paper. As a rough guide from recent published thresholds, A* boundaries on extended-tier papers tend to land in these ranges:
| Subject group | Typical A* zone | Why it varies |
|---|---|---|
| Maths (Extended) | ~85–90% | High precision expected; boundaries drop on harder series |
| Sciences (Extended) | ~80–88% | Practical/ATP papers shift the combined threshold |
| English & essay subjects | ~75–85% | Mark schemes are level-based; full marks are rare, so boundaries sit lower |
| Languages | ~80–90% | Speaking and listening components vary session to session |
The Core vs Extended trap
On Cambridge IGCSE, many subjects offer two tiers. This catches students out every single year: if you sit the Core paper, the highest grade you can be awarded is a C (grade 5 on the 9–1 scale) — even with a perfect score. If you're aiming for A/A* and your school has you entered for Core, that conversation needs to happen months before the exam, not on results day.
How examiners actually set the boundaries
- Everyone sits the paperBoundaries don't exist yet — only the raw marks do.
- Senior examiners review difficultyThey compare this session's questions and scripts against archived scripts from previous years at each grade.
- Statistics keep standards levelCohort performance data ensures an A* this year represents the same standard as an A* last year — if the paper was harder, the boundary comes down.
- Thresholds are publishedAfter results are released, the exact mark for every grade, on every component, becomes public.
Stop chasing percentages — build a buffer instead
Here's the psychological shift that separates calm candidates from anxious ones. You cannot control where the boundary lands; you can control your distance from it. So flip the goal: instead of "I need 87%", make it "I consistently score 10+ marks above last year's boundary on real past papers."
That buffer does two jobs. It absorbs boundary movement — wherever the threshold lands, you clear it. And it absorbs exam-day noise: the misread question, the ten nervous minutes, the topic you hoped wouldn't come up. Students who train with a buffer walk in knowing a bad day still lands on target — which, ironically, makes the bad day far less likely.
Results day, remarks and retakes
When results land, three numbers matter: your grade, the published threshold, and how many marks you were from the next boundary (your school's exams officer can tell you). If you're 1–2 marks below a boundary, an enquiry about results (remark) may be worth it — but know that grades can go down as well as up, so it's a genuine decision, not a free roll. If the gap is bigger, a November retake is usually the stronger play — entry deadlines fall within days of results day, so decide quickly. Our results day guide walks through the whole process step by step.
FAQ
What percentage is an A* in IGCSE?
Do IGCSE grade boundaries change every year?
Can you get an A* on a Core paper?
What counts as a pass in IGCSE?
Should I ask for a remark if I just missed a boundary?
Grade boundaries aren't a mystery — they're a moving line that rewards students who prepare with margin. Stop asking "what percentage do I need?" and start asking "how far above the boundary am I scoring on real papers?" Answer that with honest, marked practice, and results day becomes a formality instead of a lottery.
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