Being in the 90th percentile means you perform better than most of your peers: specifically, about 90% of the population or group being compared to scored at or below your value, while roughly 10% scored higher. In practical terms, you’re among the top 10% of the group in whatever metric is being measured (test scores, weights, incomes, etc.), assuming a representative distribution and the percentile definition being used. Key points to keep in mind:

• Percentile indicates relative standing, not a raw score or percentage of correct answers. For example, a score at the 90th percentile means you outperform roughly 90% of others, but it does not imply you answered 90% of questions correctly.
• There are two common ways percentiles are defined in practice (exclusive vs inclusive):
  • Exclusive definition: the percentile value is the smallest score such that at least that percentage of observations are less than or equal to it.
  • Inclusive definition: the percentile may include scores equal to the percentile value and can affect the exact cutoff slightly.
• The exact interpretation can vary by context and the method used to compute percentiles, but the core idea remains: you are higher than the vast majority of the comparison group.

If you’d like, share the specific context (e.g., a test score, a dataset, or an income distribution) and I can tailor the explanation to that scenario, including how the 90th percentile would be interpreted given the data’s distribution.