Statistical

WEIBULL.DIST Function in Excel

Returns the Weibull distribution.

Syntax

  • =WEIBULL.DIST(x, alpha, beta, cumulative)

Arguments

  • x (required): Value to evaluate
  • alpha (required): Shape parameter
  • beta (required): Scale parameter
  • cumulative (required): TRUE for CDF, FALSE for PDF

Examples

  • =WEIBULL.DIST(105, 20, 100, TRUE) - Weibull CDF - Result: 0.929

WEIBULL.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 parameters <= 0

Use cases

  • Reliability analysis
  • Failure modeling
  • Survival analysis

Frequently asked questions

  • What is WEIBULL.DIST used for? WEIBULL.DIST models time-to-failure and reliability data. It's extremely flexible - by adjusting the shape parameter (alpha), it can model increasing failure rates (wear-out), decreasing rates (infant mortality), or constant rates (random failures).
  • How do I interpret the alpha (shape) parameter? Alpha < 1: failure rate decreases over time (infant mortality, burn-in failures). Alpha = 1: constant failure rate (random failures, equivalent to exponential). Alpha > 1: failure rate increases over time (wear-out, aging). Alpha ≈ 3.5 approximates normal distribution.
  • How do I calculate reliability with WEIBULL.DIST? Reliability R(t) = 1 - WEIBULL.DIST(t, alpha, beta, TRUE). This gives the probability of surviving beyond time t. Example: with alpha=2, beta=1000 hours, reliability at 500 hours: =1-WEIBULL.DIST(500, 2, 1000, TRUE) ≈ 0.78 (78% survive).

Editorial review

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