A percentile describes a position relative to a comparison group. Percentage correct describes how many questions you answered correctly. They answer different questions, even when both are written with numbers between 0 and 100.
Compare two meanings of 80
Answering 24 of 30 questions correctly gives 80% accuracy. It does not automatically put you at the 80th percentile. If almost everyone in a reference group answered 27 correctly, 24 would fall below much of that group.
Conversely, 60% accuracy could be a high relative result on a very difficult assessment. The ranking depends on other results, not just your fraction of correct answers.
A model-based example
For an illustrative normal distribution with mean 100 and standard deviation 15, first calculate a standardized value: subtract 100 from the score and divide by 15. A score of 115 gives 1. The normal model places approximately 84.1% of its area below that point.
That is an example of a calculation using a model. It is not evidence that a score of 115 from every online test exceeds the performance of 84.1% of people. The test needs a suitable link to that distribution before the interpretation is justified.
Check the group and the convention
Useful percentile documentation identifies who was included and how ties were treated. A result described as being above 80% of website visitors is not automatically an age-matched national percentile. The sample and the comparison are different.
Avoid interpreting tiny percentile differences as precise rankings when measurement uncertainty and tied scores are substantial.
Reading a starp result
starp displays a calibrated score and percentages correct in four reasoning areas. Those skill percentages are not population percentiles. Its homepage bell curve is a reference illustration, not a distribution of verified human results. Read the scoring method before translating a score into a rank against people outside the test.
Use the free IQ percentile calculator to explore the model in either direction. For a specific value, the IQ score guide covers scores from 70 to 160.