What is the difference between probability mass function (PMF) and probability density function (PDF)?

Updated May 17, 2026

Short answer

PMF is for discrete variables, while PDF is for continuous variables.

Deep explanation

PMF gives actual probabilities for discrete outcomes, while PDF gives density, not direct probability. For continuous variables, probability is computed over intervals using integration.

Real-world example

PMF for dice rolls vs PDF for heights distribution.

Common mistakes

  • Thinking PDF values are probabilities.

Follow-up questions

  • Can PDF exceed 1?
  • How do you get probability from PDF?

More Probability interview questions

View all →