Exam season · 18 August 2026 · 5 min read
IGCSE physics grade boundaries, explained properly
Updated 25 September 2026
Every August and January the same questions arrive on my WhatsApp: what percentage is an A*? Why did the boundary move? My mock says 82% — is that an A or an A*? Grade boundaries are simpler than the internet makes them look, and understanding them changes how you revise.
Who sets the boundaries, and when
Boundaries are not fixed in advance. After every session, the exam board looks at how the whole cohort performed and sets the thresholds so that a grade means the same standard from year to year. A hard paper gets lower boundaries; a gentle paper gets higher ones. This is why last session's thresholds are a guide, never a promise.
For Cambridge 0625 Extended, the syllabus aggregate combines Paper 2 (multiple choice, 30%), Paper 4 (theory, 50%) and Paper 5 or 6 (20%). Edexcel 4PH1 combines Paper 1 (110 marks, 61.1% of the qualification) and Paper 2 (70 marks, 38.9%). In both qualifications, the final grade comes from the overall result rather than one paper in isolation.
A concrete example: Cambridge June 2026
For Cambridge 0625 Extended in June 2026, the official A* threshold ranged from 156 to 165 out of 200 across the supported component combinations; A ranged from 133 to 140. Your exact papers matter, which is why the calculator on this site asks for the component combination.
The lesson is not to memorise those figures for a future series. It is to understand the size of your margin using the correct official table. Chasing one difficult question while easy definition, unit or graph marks go unclaimed is a poor trade.
The boundary region between A and A* is often decided by accumulated execution: units dropped, definitions paraphrased too loosely, explanations without a complete chain of reasoning, and practical-analysis marks missed. Knowledge and technique both matter.
A past boundary is a useful benchmark — never a promise for the next session.
What this means for your revision
Learn every definition precisely — definition questions offer repeatable marks when the required terms are present. Master the Paper 6 routines, because practical-analysis marks can accumulate quietly. And do past papers against the real mark scheme, so you know what a mark is actually paid for.
If you want to see where you stand right now, put your latest mock marks into the grade calculator on this site — it will tell you what the remaining papers need to deliver for each grade.
Questions, explained
Choose a question for a direct answer, then explore the explanation and supporting resources. Each answer has its own link to save or share.
Can I average my Physics paper percentages to estimate the final grade?
Average raw percentages only when the published aggregation rules give those percentages equal weight and require no raw-to-uniform conversion. Otherwise use the specified weighting and conversion. Equal unit weight alone is insufficient for a modular qualification using UMS. Compare the correctly aggregated result with the matching qualification, session and component thresholds.
For Cambridge 0625 Extended, imagine scores of 32/40, 56/80 and 30/40. Using the 30%, 50% and 20% contributions gives 0.30 × 80 + 0.50 × 70 + 0.20 × 75 = 74%. On the 200-mark weighted scale that is 148, obtained as 1.5 × 32 + 1.25 × 56 + 30. This is an illustrative score, not a prediction of a future grade.
Does a grade-boundary percentage tell me what proportion of students earned that grade?
No. A mark percentage describes the score required on that assessment; the proportion of students receiving a grade describes the cohort's results. They are different measures. A boundary of 80% would not mean that 80% of candidates obtained that grade.
Likewise, a low raw-mark boundary does not by itself establish that one qualification is easier than another. Papers differ in demand, structure and marking, while boundaries are used in awarding grades. When planning revision, use the appropriate historical threshold as context and focus on which skills are costing you marks. Avoid converting a score into a percentile without the relevant distribution data.
Why can my school mock grade differ from an online grade calculator?
Your mock may use selected questions, adjusted boundaries or a school assessment policy rather than a complete official paper. An online calculator is only as relevant as its supported qualification and session. Ask how the school calculated the grade before comparing the two results.
A test containing only electricity questions may overrepresent your strongest or weakest topic. Even if its percentage matches a full-paper score, the coverage is different. Ask which paper, maximum mark and boundary were used, then use the marked questions to identify improvements. Treat a calculator result as an estimate against the named historical data, not as an official grade award or guaranteed future threshold.
Can the same raw-percentage method calculate an Edexcel IAL Physics grade?
No. Edexcel IAL unit raw marks are converted to UMS, and the qualification combines the relevant UMS results. For the six-unit Physics A*, Pearson requires at least 480/600 UMS overall and 270/300 across A2. These are UMS requirements, not raw-paper percentages.
For an illustrative case, 220 AS UMS plus 270 A2 UMS gives 490 overall and meets both numerical A* conditions. By contrast, 250 plus 260 gives 510 overall but misses the 270 A2 condition. Use the correct unit results and qualification entry; do not average six raw-paper percentages. Your centre should confirm the cash-in and any resit details.