Statistical

EXPON.DIST Function in Excel

Returns the exponential distribution.

Syntax

  • =EXPON.DIST(x, lambda, cumulative)

Arguments

  • x (required): Value to evaluate
  • lambda (required): Rate parameter
  • cumulative (required): TRUE for CDF, FALSE for PDF

Examples

  • =EXPON.DIST(0.5, 2, TRUE) - Exponential CDF - Result: 0.632

EXPON.DIST for data analysis

  • Confirm whether you need entire columns, filtered subsets, or distinct values.
  • Use [COUNTIFS](/functions/countifs/) and [SUMIFS](/functions/sumifs/) for multi-criteria metrics.
  • Pivot tables complement single-cell statistical formulas for exploration.

Common errors

  • #NUM! if x < 0 or lambda <= 0

Use cases

  • Reliability analysis
  • Queuing theory
  • Survival analysis

Frequently asked questions

  • What is the exponential distribution used for? Exponential distribution models time between events in a Poisson process: time between customer arrivals, time until equipment failure, radioactive decay. It's 'memoryless' - the probability of an event doesn't depend on how long you've waited.
  • How do I calculate probability of failure within time T? Use =EXPON.DIST(T, failure_rate, TRUE). If average time between failures is 100 hours, rate=1/100=0.01. Probability of failure within 50 hours: =EXPON.DIST(50, 0.01, TRUE) = 39.3%.
  • What is the relationship between lambda and mean? Lambda (λ) is the rate parameter. Mean = 1/λ. If average time between events is 5 minutes, λ = 1/5 = 0.2 per minute. Higher λ means events happen more frequently, shorter average time between events.

Editorial review

  • Reviewed by Excel.Directory Editorial Team. Updated May 2026.