Weibull Analysis Toolkit — Life Data Analysis Excel Template (Censored Data)

Your failure history already knows when things wear out. This toolkit makes it say so — in the spreadsheet you already have.

The Weibull Analysis Toolkit fits a two-parameter Weibull distribution to failure-time data entirely inside Excel or Google Sheets — no statistics software, no macros, no add-ins. Enter each item's age when it failed, or its age when last seen still running (a suspension), and the workbook sorts the data, applies Johnson adjusted ranks for the suspensions, computes Benard median ranks, and fits the line: beta, eta, and R-squared, calculated live. A probability-plot tab shows your points against the fitted line, and a results tab turns the fit into the numbers maintenance actually runs on.

What it calculates for you
• Beta (shape) with a plain-language pattern read: below 1 early-life, near 1 random, above 1 wear-out — and what each pattern tells you to do differently
• Eta (characteristic life), B1 / B5 / B10 / B50 / B63.2 / B90 lives, and MTTF
• A reliability calculator: enter any age, get R(t), F(t), and the hazard rate at that age
• A PM-interval helper: enter a target reliability (or a max share failed) and get the replacement / inspection age that delivers it
• Up to 50 lives per fit — failures and suspensions (censored data) handled properly, not deleted

The worked example (fictional, fully filled in the workbook)
Twenty mechanical-seal lives from a set of identical process pumps: 16 failures, 4 still running. The fit returns beta 2.20 (a genuine wear-out pattern), eta 2,373 hours, R-squared 0.975, B10 of 851 hours and an MTTF of 2,102 hours — and the guide walks the whole analysis end to end, including the sensitivity check that exposes two installation failures hiding in the data. Every number in the guide reconciles with the workbook.

Designed by a Reliability Engineer.

This product was designed by a Reliability Engineer with 15+ years in the industry, including experience across defense, aerospace, and weapons programs. He has built and implemented reliability-centered maintenance programs at multiple facilities — so the logic in these pages is not textbook theory. It is the same structure he has put into practice on real equipment, with real maintenance teams: the calculations are shown, not hidden — every number in this workbook can be traced back to its inputs and its method. Every worksheet is built to be used the way the work is actually done — in a session, on a plant floor, with the people who own the equipment.

Free updates included — if this product is corrected or improved, the updated edition is delivered free to everyone who purchased it, via the store.

What's included
• Weibull-Analysis-Toolkit.xlsx — 5 tabs: Start Here · Data & Fit · Weibull Plot (with the probability-plot chart) · Results & Decisions · Worked Example. Ships empty, ready for your data; the example lives on its own tab
• Weibull-Analysis-Guide.pdf — 16 pages: the method in plain language, collecting failure-time data (and what a suspension really is), reading beta honestly, the worked example, turning a fit into interval and spares decisions, mixed-mode and small-sample warnings, the limits of the method, plus two printable worksheets

Who it's for
Reliability engineers, maintenance managers setting replacement ages, plant and project engineers comparing populations, and consultants who need to show the plot behind the claim.

What you need
Microsoft Excel or Google Sheets. Standard formulas only — the same file works identically in both. The fit is median-rank regression, the transparent hand-checkable method (the guide explains how it differs from maximum-likelihood fitting and when that matters).

Scope
This is a decision-support tool for qualified professionals. A fit summarizes the history you enter; it is not a certification of equipment fitness or future performance, and any interval change follows your site's management-of-change process. Safety-related and regulated components follow their own requirements regardless of what a fit suggests.

Instant download. Print the guide's worksheets as often as you need.