Some examinations are difficult because they cover an enormous syllabus, while others demand exceptional reasoning, professional knowledge, practical skills, or performance under intense time pressure. There is no universally accepted ranking of the hardest exam in the world, because these tests serve very different purposes. However, several examinations are widely known for their demanding selection processes and high level of competition.
Exams Known for Exceptional Difficulty
1. Mensa Admission Tests

Mensa is an international organization for people who perform exceptionally well on approved intelligence tests. Rather than having one universal examination, Mensa accepts qualifying scores from recognized tests. Admission generally requires performance within the top 2% of the relevant population according to an accepted test.
2. Graduate Record Examination (GRE)

Many colleges adopt the GRE for their postgraduate enrollment. This exam evaluates the Verbal Reasoning, Quantitative Reasoning, and Analytical Writing skills of a candidate. In order to score well, a student should possess the right combination of knowledge, reasoning skills, vocabulary, time management skills, and technical know-how regarding the computer-based test program.
3. Chartered Financial Analyst (CFA)

The CFA exam has three stages and covers various concepts including financial analysis, economics, several accounting concepts, investment portfolio management, and ethics. Any candidate should understand all the basic concepts and be able to apply them in practical terms.
4. Gaokao

The National College Entrance Examination of China (Gaokao) is one of the hardest exams in the world. The exam contributes to the university admissions process and has an image of a difficult test because of intense academic requirements, long study preparation, and high competition for getting into the universities.
5. UPSC Civil Services Examination
The UPSC Civil Services Examination comprises three parts: Preliminary exam, Main exam, and Personality test. The wide syllabus includes history and geography, governance, politics, economics, ethics, and affairs. The fact that there are multiple levels of testing makes preparation harder.
6. JEE Advanced

JEE Advanced is a significant entrance examination for entry into degree programmes offered by the IITs. The focus of this examination is on practical problem-solving and comprehensive understanding of the various concepts involved in Physics, Chemistry and Mathematics. Candidates may be required to represent several concepts rather than simply expect that they should remember their formulas.
7. California Bar Examination
The California Bar Examination is a test to determine whether the candidate possesses the necessary skills and knowledge required for the practice of law in California. It has several components to examine the various aspects of law and the practical skills of the candidates.
8. CCIE Certification

The Cisco Certified Internetwork Expert certification, or CCIE, is an examination taken by professionals and those having some experience in the field of networking. According to the topic, they have to show that they possess theoretical knowledge and practical knowledge about the configuration and troubleshooting in networking as well. The most significant part of this certification is the hands-on laboratory examination where the candidates must demonstrate their practical skills, solving special problems.
9. All Souls Examination
The All Souls Examination at Oxford is associated with selection for academic fellowships at All Souls College. It has a reputation for demanding independent thinking, argument development, broad knowledge, and originality. Its highly selective nature adds to its difficulty.
10. JLPT N1
The JLPT N1 is known as the most difficult JLPT level. The focus at this level is on advanced proficiency in reading, listening, and comprehension as well as on vocabulary and grammar knowledge. It would usually take non-Japanese students years of thorough training in order to pass this exam.
Why are these exams difficult?
Exams can be difficult for various reasons. Some of them require long curricula while others require you to apply thinking skills, practical skills, or professional judgment. The number of participants can make the situation competitive. Comparing passing rates might be misleading because in some cases exams are filtered out based on competitive selection, and in others it is about just passing the exam.
How to prepare for difficult exams?
To succeed in preparing for exams, you need to know the syllabus and the structure of the exam. Make a realistic timetable and split the exam content into smaller goals. Regularly do past papers and practice tests.
It is also useful to maintain an error log. Recording repeated mistakes can reveal weak areas and prevent the same errors from occurring again. Along with studying, adequate sleep, breaks, exercise, and a balanced routine can help maintain concentration during long preparation periods.