The Hardest IB Classes, Ranked by Real Data (2025)

Every IB student has heard the rumours. "HL Chemistry is a grade killer." "Nobody gets a 7 in History." "Math AA HL is only for geniuses." Some of those rumours are true. Some are completely backwards. In this guide, we rank the hardest IB classes using the IB's own official numbers — the May 2025 final statistical bulletin, covering 202,102 students in 153 countries. No guesswork. Just the actual average grade and the actual percentage of 7s for every major subject.

Quick answer: By average grade, the hardest IB classes in May 2025 were Math AI SL (average 3.9 out of 7), Sports Exercise Science SL (3.8), Visual Arts SL (4.0), Design Technology SL (4.1), and Physics SL (4.2). But if "hard" means "hard to get a 7", the toughest classes were English A Literature HL (only 1.5% scored a 7), History HL (2.6%), and Visual Arts HL (2.6%). Math AA HL — the subject with the scariest reputation — actually had a higher average (4.9) than the worldwide mean and gave out 7s to 16.4% of students.

Surprised? Most people are. Let's dig into the numbers.

How do we decide which IB classes are hardest?

The fairest way to rank the hardest IB classes is to use the IB's own results data, measured two ways: the average grade in each subject, and the percentage of students who earned a 7. All the numbers in this post come from the IB Diploma Programme final statistical bulletin for May 2025, published by the International Baccalaureate on ibo.org. That session had 202,102 students, an average total score of 30.6 out of 45, an average subject grade of 4.9 out of 7, and a pass rate of 81.9%.

Why two measures? Because they tell different stories.

• Average grade shows how the typical student in that class performed. A low average means most students struggled.

• Percentage of 7s shows how hard the top grade is to reach. A subject can have a decent average but almost no 7s — which matters a lot if you're chasing a top university offer.

One warning before the tables. These numbers measure who takes the subject as much as the subject itself. We'll explain that fully in the selection bias section below. Keep it in mind as you read.

The hardest IB classes at a glance

The single hardest large IB class by average grade in May 2025 was Math AI SL, with an average of just 3.9 out of 7. Here are the toughest widely-taken subjects, ranked by average grade:

For comparison, the worldwide average grade across all subjects was 4.7. Every class in this table sits below it.

Notice something? The list is full of SL classes. That's not because SL is harder than HL — it's selection bias at work. Students who choose a subject at Higher Level (HL, the deeper two-year version) usually like it and are good at it. Students in the Standard Level (SL) version often took it because they had to fill a group. More on that soon.

Which IB classes are hardest to get a 7 in?

English A Literature HL is the hardest major IB class to get a 7 in — only 1.5% of its 30,239 students managed it in May 2025. That's roughly 1 student in every 67. Here's the "hardest to top" ranking:

Now compare the other end. In Physics HL, 19.2% of students got a 7. In Math AA HL, 16.4% did. In Chemistry HL, 15.0%.

Read that again, because it flips the usual story. The "scary" math and science HLs hand out 7s at ten times the rate of English A Literature HL or History HL. If your dream university offer needs a 7, a big essay subject at HL is statistically a far riskier place to chase it than Physics HL.

Why? Essay subjects are marked against judgment-based criteria, and examiners keep the top band tiny. Math and science exams are marked right-or-wrong, so a prepared student can physically collect every mark. You can't "collect every mark" in a literature essay.

Are the sciences the hardest IB group?

Yes — sciences and math were the two lowest-scoring IB subject groups in May 2025, averaging 4.5 and 4.4 while every other group averaged 4.8 or higher. Here's the full group table:

Within the sciences, the three core subjects stack up in a way that surprises most students:

Biology HL — the science everyone calls the "safe" choice — had the lowest HL average of the three and barely a third of Physics HL's 7 rate. Biology isn't conceptually harder than Physics. It's just enormous. The syllabus buries you in content, and exam questions demand precise wording that students constantly half-remember. Physics HL, meanwhile, attracts a small, confident, math-strong crowd — and rewards them.

The other trap in Group 4 is Environmental Systems and Societies (ESS) SL. Students pick it as the "easy science". Its average? Just 4.3, with only 5.0% earning a 7 — worse odds of a top grade than Chemistry SL. Easy to pass, genuinely hard to top.

Is Math AA HL really the hardest IB class?

No — by the IB's own May 2025 data, Math AA HL had an average grade of 4.9, above the worldwide subject average of 4.7, and 16.4% of its students earned a 7. Out of 24,966 students taking it, roughly 1 in 6 got the top grade. Those are some of the best odds of a 7 anywhere in the IB.

The hardest math class by results is actually Math AI SL, averaging 3.9 — the lowest average of any subject with more than 40,000 students. Here's the full picture:

Does that mean Math AA HL is easy? Absolutely not. The content — proofs, calculus, complex numbers — is the deepest math the IB offers. But the students sitting it chose the hardest course on purpose. They're the strongest math cohort in the programme, and their results show it. Meanwhile, Math AI SL (Applications and Interpretation, the statistics-flavoured course) collects everyone who wants the smallest possible dose of math. Many arrive with shaky algebra, and 39.4% of them finished on a grade 3 or below.

The honest conclusion: for a strong math student, Math AA HL is demanding but very winnable. For a weak math student, no math course is safe — even "easy" Math AI SL punishes gaps in the basics. If you're choosing between the two tracks, our guide to Math AA vs Math AI breaks down exactly who each course suits. And if math is the subject you're most worried about, a specialist IB Math tutor closes those foundation gaps faster than any other fix we know.

Why are History HL and English A Literature HL so brutal?

History HL and English A Literature HL are the hardest mainstream HL classes because both bury students in reading and both cap their top band hard — just 2.6% and 1.5% of students got a 7 in May 2025. They're worth their own section, because 67,000+ students take them combined.

History HL (37,228 students, average 4.4) is the lowest-averaging HL of any major subject. The problem isn't understanding history. It's volume and technique. You study multiple regions and eras in deep detail, then face three essay papers where you must build arguments — fast, under time pressure, with evidence recalled from memory. In May 2025, 20.5% of History HL students finished on a grade 3 or below. That's one in five.

English A Literature HL (30,239 students, average 4.6) posts a respectable-looking average — and the single worst 7 rate of any large IB class. The middle grades are reachable: 37.4% of students land on a 4. But the jump from "good essay" to "top-band essay" is the widest gap in the IB. Examiners reserve 7s for writing with genuine critical flair, and no amount of memorising guarantees that.

If you take either subject, the play is the same: master the mark scheme early, practise timed essays relentlessly, and get feedback on your writing — not just your knowledge. Our guide on how to score a 7 in the IB covers the technique side in detail.

What actually makes an IB class hard?

Three things make an IB class hard: the amount of content, the way it's marked, and the students you're graded alongside. Every "hard subject" story in the tables above comes down to one of these.

1. Content volume. Biology HL and History HL aren't full of impossible ideas. They're full of ideas — thousands of them, each of which can appear on the exam. Subjects like this punish students who start revising late. There is simply too much to cram.

2. Marking style. Right-or-wrong subjects (math, physics, chemistry) let a well-drilled student collect every mark. Judgment-marked subjects (English, History, Visual Arts) hold their top band to a tiny share of entries, no matter how well the cohort performs. That's why Visual Arts SL — a subject nobody calls "hard" — gave a 7 to just 0.7% of students, the lowest rate in this entire post.

3. The cohort. A grade in the IB reflects your work measured against set standards — but who chooses the class shapes its statistics completely. Which brings us to the most misunderstood idea in this whole topic.

Selection bias: why "hardest" stats lie a little

Selection bias means a subject's average grade depends on who signs up for it, not just how hard it is. This is the single most important idea for reading any table in this post.

Chinese B HL averaged 6.0 in May 2025, with 35% of students getting a 7. Is it the easiest class in the IB? Of course not — many of its students already speak Chinese at home. The course isn't easy; the cohort is unusually prepared.

Flip it around. Math AI SL averaged 3.9. Is it the hardest math course? No — it's the least demanding math course, taken by the students least confident in math. The course is easier; the cohort is less prepared. The stat measures both at once and can't tell them apart.

So use the numbers this way: they tell you what happened to the typical student who chose that class — and that's still genuinely useful. If you're an average-at-math student considering Math AI SL, the 3.9 average is describing people like you. If you're a strong math student considering AA HL, the 4.9 average is describing people like you too.

What's the hardest IB subject combination?

The statistically hardest IB combination stacks the lowest-averaging class from each group: English A Literature HL, a language ab initio, History HL, Biology HL, Math AI SL, and Visual Arts. A student performing at the world average in each of those subjects would finish several points below the global average of 30.6 — before TOK and the Extended Essay add their core points.

But real difficulty is about workload collisions, not just averages. The combinations that actually break students pair multiple heavy-content subjects together:

• Biology HL + Chemistry HL + Psychology HL — three memorisation monsters. Every exam season becomes a content avalanche.

• History HL + English A Lit HL + Global Politics HL — three essay subjects. You will write more than some university students.

• Math AA HL + Physics HL + Chemistry HL — the classic engineering stack. Conceptually the deepest combination the IB offers, though (as the data shows) its students score well.

Before locking in choices, check what your target universities require, then balance one heavy subject against lighter ones. Our complete guide to IB subjects walks through every group and how the choices fit together. And once you have real grades coming in, you can test scenarios with our free IB score calculator to see how each subject feeds your total out of 45.

Which IB classes are the easiest?

By the May 2025 data, the highest-scoring IB classes were second-language B courses — Chinese B HL averaged 6.0 and English B HL averaged 5.6 — along with Geography HL (5.3), Economics HL (5.2), and Global Politics HL (5.1). Among the sciences and math, nothing qualifies as "easy": the friendliest options were Chemistry HL and Physics HL for well-prepared students, purely because their 7 rates (15.0% and 19.2%) beat everything else in their groups.

Treat the "easy" list with the same selection-bias warning. Language B courses score high partly because many students study a language they already partly know. Geography HL and Economics HL genuinely do post strong numbers across huge cohorts, though — if they fit your university plans, they're statistically kind choices.

The honest summary: there are no easy IB classes, only classes that fit you well or badly. A subject that matches your strengths will always feel — and score — easier than a statistically "easy" subject that doesn't.

How should you actually choose your subjects?

Choose IB subjects on three tests — university requirements, your genuine strengths, and workload balance — and only then glance at difficulty statistics. Here's the order that works:

1. University first. If your target course requires Chemistry HL or Math AA HL, that decision is made. A "hard" required subject beats an "easy" irrelevant one every time.

2. Strengths second. Look at your last two years of grades honestly. Strong essay writer? History HL's 2.6% seven-rate should worry you less. Struggle with extended writing? That stat is a genuine red flag.

3. Balance third. Avoid stacking three content monsters or three essay subjects. Mix marking styles so your exam season spreads the load.

4. Stats last. Use the tables above to set expectations and plan support — not to dodge subjects you need.

And plan for the hard ones rather than fearing them. Every low average in this post belongs to a subject where thousands of students still scored 7s. They did it with early starts, past-paper practice, and — when a subject fought back — targeted help. That's exactly what we do at Educifly: hand-matched, one-on-one specialist tutors for every IB subject in these tables, from Math AA HL to English A Literature. A free trial class is the quickest way to see whether the hardest class on your timetable is really as hard as its reputation.

Frequently asked questions

What is the hardest IB class?

By average grade, the hardest large IB class in May 2025 was Math AI SL, averaging 3.9 out of 7 across 42,968 students. By percentage of top grades, the hardest was English A Literature HL, where only 1.5% of students earned a 7. Sports Exercise Science SL had the lowest average of any sizeable subject at 3.8.

What percentage of IB students get a 7?

Across all subjects in May 2025, 8.3% of grades awarded were 7s. The rate varies hugely by subject: 19.2% in Physics HL and 16.4% in Math AA HL, but just 2.6% in History HL and 1.5% in English A Literature HL.

Is IB Math AA HL the hardest IB class?

No. Math AA HL has the deepest math content in the IB, but its results are strong: a 4.9 average and 16.4% of students scoring a 7 in May 2025 — better than the worldwide average. Its students are a self-selected, math-confident group, which lifts the statistics. Hard content, good outcomes.

Which IB science is the hardest?

Biology HL had the lowest average (4.5) and lowest 7 rate (7.2%) of the three core sciences at HL in May 2025, mainly because of its huge content load. Physics HL and Chemistry HL averaged 4.9 and 4.8. At SL, Physics posted the lowest average of the three at 4.2.

Is History HL the hardest humanities subject?

Yes, by the numbers. History HL averaged 4.4 in May 2025 — the lowest of any major Individuals and Societies subject — and only 2.6% of its 37,228 students earned a 7. One in five finished on a grade 3 or below. The essay workload and volume of detail are the main causes.

Why is it so hard to get a 7 in English A Literature HL?

Because the top band is tiny and judgment-marked. Only 1.5% of English A Literature HL students got a 7 in May 2025 — the lowest rate of any large IB class. Middle grades are common (37.4% scored a 4), but examiners reserve 7s for exceptional critical analysis, which no memorisation strategy guarantees.

Is ESS actually an easy IB subject?

No. Environmental Systems and Societies SL averaged just 4.3 in May 2025, and only 5.0% of its 22,078 students earned a 7 — a lower top-grade rate than Chemistry SL. ESS is easier to pass than a traditional science, but it's one of the harder subjects in which to score a 7.

What is the easiest IB class?

Statistically, Language B courses score highest — Chinese B HL averaged 6.0 and English B HL 5.6 in May 2025. Among mainstream subjects, Geography HL (5.3) and Economics HL (5.2) had the strongest results. Remember the selection-bias caveat: high averages partly reflect well-prepared cohorts.

Does taking hard IB classes look better to universities?

Universities care most that you took the subjects their course requires, at the right level, and scored well. A 7 in a required HL beats a 7 in an unrelated "harder" subject. Admissions teams know the IB well — they read your subject choices in context rather than rewarding difficulty for its own sake.

What was the average IB score in 2025?

The average total score in the May 2025 session was 30.6 points out of 45, with an average subject grade of 4.9 for diploma students and a pass rate of 81.9%. Around 9.8% of diploma students scored 40 points or more.

Should I avoid hard IB classes to protect my total score?

Not if you need them. Dropping a required subject to protect your average usually costs more at university application time than a slightly lower grade would. Avoid unnecessary difficulty — don't stack three content-heavy HLs for pride — but take the subjects your goals demand and plan support early.

Can a tutor really help in the hardest IB subjects?

Yes — the hardest subjects respond best to targeted help, because their difficulty is specific: technique in essay subjects, foundations in math, volume management in biology. A specialist who knows the mark scheme can show you exactly where grades are won. Thousands of students score 7s in these subjects every session; preparation, not talent, separates them.

Written by the Educifly team — IB and IGCSE subject specialists teaching students in 20+ countries since 2018. All statistics in this post come from the IB Diploma Programme and Career-Related Programme Final Statistical Bulletin, May 2025, published by the International Baccalaureate.