How many IGCSE grades are there? A* to U, 9 to 1, and how they compare with Thai school grades
IGCSE is graded either A* to G or 9 to 1, with U below the lowest grade. This guide puts it in tables: roughly what score each grade takes, what it tells you about your child, how far it lines up with the 8-level scale of Thai schools, and the strengths and weaknesses of the IGCSE way of examining.
The short answer
Letters: A*, A, B, C, D, E, F, G (8 grades) · below G = U (Ungraded), not on the certificate.
Numbers: 9 to 1 (9 is highest) · below 1 is also U · which scale applies depends on the syllabus code the school enters (e.g. Cambridge Chemistry 0620 = A*–G, 0971 = 9–1, Edexcel 4CH1 = 9–1).
The grade most people treat as the pass line is C, or 4.
No official body converts IGCSE grades into Thai grades; you can only compare what the same score earns in each system.
IGCSE grades: what % each takes and what it tells you
The numbers come from the real June 2026 IGCSE Chemistry thresholds. Other subjects and series differ, but the shape is similar: a C takes less than half the marks, an A* about 85%.
Tap a row to highlight it
| Grade | Min.* | 9–1 | What it tells you |
|---|---|---|---|
| A* | 84.5% | 9/8 | Top grade: nearly every mark, written and applied questions included |
| A | 69.5% | 7 | Secure content and written answers; ready for science A-Levels |
| B | 54.5% | 6/5 | Knows the core; still drops written and calculation marks |
| C | 40% | 4 | The pass most schools and universities look for; Cambridge says A*–C prepares for AS & A Level |
| D | 34% | 3 | A pass, but below what further study usually asks for |
| E | 28.5% | 2 | Partial knowledge; basic questions only |
| F | 23% | 2 | Limited |
| G | 17.5% | 1 | The lowest grade that goes on the certificate |
| U | below G | U | Ungraded: below G; on the statement of results, not the certificate |
What the syllabus itself says about grades
Cambridge's 0620 Chemistry syllabus says candidates who achieve A* to C "are well prepared to follow a wide range of courses including Cambridge International AS & A Level Chemistry". That is why C is the line schools and universities tend to use.
In subjects split into Core and Extended, Core can reach a C at most. An A or A* needs Extended (more on tiers).
U (Ungraded) means the mark did not reach G. It appears on the statement of results, not on the certificate.
How A*–G and 9–1 line up
Cambridge confirms only three matching points, at the bottom of each grade: 7 = A · 4 = C · 1 = G.
A 9 is not simply an A*: Cambridge sets grade 9 by a separate method, and spaces 8, 6, 5, 3 and 2 evenly between the anchors. Tables that map every number to a letter are approximations, not official figures.
Universities treat both scales equally, so the school's choice of scale does not disadvantage your child.
Against Thai school grades: the same %, a different meaning
Thai schools under the Basic Education Core Curriculum B.E. 2551 use a standard 8-level scale: 80% and above = 4 · 75 = 3.5 · 70 = 3 · 65 = 2.5 · 60 = 2 · 55 = 1.5 · 50 = 1 · below 50 = 0. Famous state schools and ordinary ones use it alike; what differs is how hard the teachers' own tests are.
IGCSE works the other way round. One paper is sat worldwide, set hard enough to separate strong candidates, and the cut-offs follow how hard that paper turned out. 40% in IGCSE Chemistry can be a C; in a Thai school, 40% is a 0.
Drag the score below and switch the paper set: the same % can land on different grades.
IGCSE Chemistry 0620
B
June 2026 thresholds
Thai school, 8-level scale
2
satisfactory
The same 60% means different things. IGCSE papers are set hard and the cut-offs follow each paper's difficulty, while Thai schools use a fixed 80% = 4 in every subject. Switch the paper set: the same % can land on a different grade.
How to read your child's grades (our view)
A 4 in school chemistry does not predict an A* at IGCSE: the papers test differently, and IGCSE answers have to be explained in written English.
The other way round, 55% on an IGCSE paper may be a B, a better result than the number suggests. Judge by the grade and that series' thresholds, not the raw %.
The useful measure is how many marks separate your child from the next grade, and where the marks go (see how far C is from A*).
Strengths of the IGCSE way of examining
Real written answers: in Extended chemistry, half the grade (50%) comes from Paper 4, which is written, not multiple choice (more on Paper 4).
Thinking, not only recall: the syllabus puts 30% of marks (AO2) on handling information and problem-solving, and says questions may use information candidates have not seen, to be solved by applying principles to a new situation.
Practical skills: another 20% (AO3) assesses planning experiments, recording observations, evaluating methods and suggesting improvements.
One standard worldwide: the same papers and thresholds in every country, so grades compare internationally, with two series a year (June · November).
Weaknesses, and what to watch
English is an extra load: understanding the chemistry but missing the wording still loses the mark (learning in Thai, answering in English).
Marked to a mark scheme: "thinking well" is not enough; answers need the keywords examiners look for, which takes its own practice.
Thresholds move every series: there is no fixed % to aim for, so build a margin.
The grade rests mainly on the final exams, not on coursework built up through the year as Thai school grades are. A bad day means waiting for the next series.
Applying to Thai medicine through กสพท still requires the ทปอ. tests in Thai (medicine requirements).
Learn with Boom-Tutor
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Notes
Sources: the Cambridge IGCSE Chemistry 0620 syllabus (exams 2026–2028) · Cambridge's June 2026 0620 grade threshold table · Cambridge's "How 9–1 grading will work" page · the 8-level scale in the assessment guidelines of the Thai Basic Education Core Curriculum B.E. 2551, checked 25 October 2026. There is no official conversion between IGCSE and Thai grades; comparisons here are of raw percentages only.
Try: all 12 IGCSE Chemistry topics, interactive, on one page
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