5 Why Root Cause Analysis

Identify root causes by repeatedly asking why. Export PNG/PDF.

Find the root cause by repeatedly asking “why”, mark the root and review a simple timeline. Autosaves in your browser and exports PNG / PDF. Ships with templates and practice demos you can load into the worksheet, fully online with no signup.

Root CauseProblem AnalysisProcess ImprovementExport PNG/PDF

5 Why Root Cause Analysis

Identify the root cause by asking "why" repeatedly.

Problem

Why Chain

Why 1

Root cause

Up to five layers. Stop early if the root cause is identified.

Derivation Timeline

Problem

(empty)

Why 1

(empty)

Quick Guide

State the problem/symptom in one sentence.
Ask “why” iteratively (3–5 times) to reveal root causes.
Mark the actionable cause as the root.
Review the problem → why chain → root via a simple timeline.
Export PNG/PDF for meetings or retrospectives.

Related Models

Critical Thinking

Evaluate claims and evidence with a structured approach, spot logical fallacies, and make resilient judgments

Featured Templates

Manufacturing Defect: Early Failure Spike

manufacturingqualityprocess

A batch shows significantly higher early-failure rate after shipment

Failures occur within 48 hours after assembly
Cold solder joints cause poor contact
Reflow profile mismatched with new solder paste
Process validation not updated after supplier switch
ECN flow lacks a mandatory re-validation checkpoint for material change

Delivery Delay: Late Inbound

supply chainproject

Customer delivery delayed two weeks from commitment

Key component inbound is late
Capacity ramp slower than expected after subcontractor change
Special jigs for customer spec not ready in time
Change request not propagated to jig procurement list
Change order lacks cross-team notification and BOM linkage

Customer Complaint: App Stutter

experienceperformance

App rating drops with frequent "laggy" complaints in the last month

Home page load time increased significantly
Too many serial API calls after marketing module added
Legacy analytics SDK enforced at first paint
No lazy-loading or sampling strategy
No pre-release performance gate + analytics policy review

Safety Incident Investigation (EHS)

EHSsafety

Minor injury at construction site due to tool slip during operation

Operator did not wear cut‑resistant gloves as required
Pre‑shift safety briefing missed new risks for this task
Work instruction not updated with fixation/inspection for the new tool
Contractor training records missing; qualification not verified
Contractor management lacks mandatory "Level‑2 safety training + tool inspection" before entry

CAPA: Corrective & Preventive (Quality)

CAPAquality

Customer sampling found label information inconsistent with batch records

Label print template not aligned with new ERP field mapping
Night shift handover skipped batch number cross‑check
Pre‑shipment sampling SOP lacks label vs. batch ledger comparison
Permission setting allowed ad‑hoc edits without approval
QMS lacks dual checks: "label change review + sampling verification"

Practice

Expand to view demos and load them into the worksheet.

FAQ

When is 5 Why a good fit?

Great for single‑dominant‑cause issues like process slips, recurring defects, or delays. For multi‑factor or correlation‑heavy problems, pair with data analysis and experiments.

How does it relate to Fishbone, Six Sigma, 8D, and 5W2H?

Fishbone enumerates possible causes; 5 Whys drills down to an actionable root. Six Sigma/8D are closed‑loop improvement systems; 5W2H structures the action plan. This tool focuses on 5 Whys and only explains the relationships here.

When should I avoid using only 5 Whys?

If multiple causal chains interact or statistical validation is required, 5 Whys alone can oversimplify. Use it with data analysis, experiments, or audits.

What is a good stopping rule?

Stop at a controllable, actionable factor with reasonable cost. Avoid drifting into macro or uncontrollable layers; converge at the controllable level with a validation plan.

Source and misuse tips?

Often linked to the Toyota Production System. A common misuse is blaming people or staying at surface descriptions. Prefer verifiable, changeable process factors.