5 Whys worksheet

Build an evidence-led causal chain. Stop when the cause is verified, not when a box is full. This free 5 Whys template, also called a 5 why template or 5 Whys worksheet, keeps each answer tied to its evidence so the chain ends at a cause you have tested rather than one the team agreed on.

What you can download

Available files: PDF. Each PDF includes the blank form first, a fictional completed example and instructions. The download is free; enter your email to receive a secure link valid for seven days. Product-news consent is optional.

The blank worksheet is one A4 page. The header records the investigation reference and date, product and lot, team, observed effect, evidence reference and owner. Below it sit a box for the observed problem (what, where, when and extent, with facts kept apart from assumptions), the why chain table with columns for each why and proposed cause, the evidence or test, and whether it is supported along with any uncertainty, then boxes for the verified cause and countermeasure and the effectiveness check, and a sign-off strip.

What a good 5 Whys analysis includes

• An observable problem. “12 of 240 parts had undersize holes”, confirmed with a verified gauge, not “quality is poor”.
• Evidence on every line. Each why has a test, measurement or record beside it.
• Visible alternate branches. Causes that were considered and excluded stay on the sheet with their evidence.
• Honest uncertainty. A why that has not been proven is marked as uncertain, not written as fact.
• A countermeasure with an owner. The fix is tied to the verified cause, not to the last box filled.
• An effectiveness check. A measure, due date and reviewer to confirm the problem has gone.

How to run a 5 Whys

1. Write the problem as an observation with its extent and evidence reference.
2. Ask why it happened and write the proposed cause with the test that would confirm it.
3. Test it. If it is supported, ask why that cause happened; if not, record it as excluded and try another branch.
4. Keep going until you reach a cause the team can control and a countermeasure would stop recurring. That may be fewer or more than five levels.
5. Record the verified cause, the countermeasure and its owner.
6. Set an effectiveness check with a measure and date, and move the record into an 8D, CAPA or A3 if containment or approvals are needed.

Completed manufacturing example

The example traces an undersize hole to reamer wear, verifies that cause with a replacement-tool trial and excludes gauge error through a cross-check. A further question about why wear history was not reviewed remains uncertain.

Stop at the evidence, not at exactly five boxes. Keep an unverified branch open and use a fishbone when several cause families need exploring. An 8D or CAPA can carry containment, approvals and longer-term effectiveness checks.

Investigation RCA-18 starts from 12 of 240 B42 parts in lot L-260912 with holes below 10.00 mm. The chain reads:

1. Why undersize? Reamer wear, supported by replacement-tool trial T-18.
2. Why was the reamer not replaced earlier? There is no life limit, supported by reviewing tool instruction WI-20.
3. Why is there no limit? Wear history was not reviewed, still uncertain and waiting on an interview with the owner.
4. Alternate branch: gauge error, excluded by a reference-gauge cross-check.

The countermeasure is a validated replacement limit and a 30-part inspection interval. The effectiveness check reviews three lots by 12 October with a target of zero undersize readings, and the unverified system-cause branch stays open until there is evidence.

Common 5 Whys mistakes

• Stopping at “human error”. Ask why the process allowed the error; the answer is usually a method, tool or training gap.
• Following one chain only. Problems often have more than one contributing cause.
• Answers without evidence. A chain built from opinions can sound convincing and still be wrong.
• Forcing exactly five. Padding the chain to five boxes, or cutting it short, both lose the real cause.
• Skipping the effectiveness check. Without it, you cannot say the countermeasure worked.

5 Whys, fishbone or full root cause analysis?

The 5 Whys goes deep on one line of causes; a fishbone diagram goes wide across people, machine, method, material, measurement and environment first. When a problem reaches a customer or needs containment and formal approvals, carry the chain into a root cause analysis or an 8D report.

When to use this template

A discussion chain is not proof. Avoid blaming a person where the process conditions remain unexplained.

Continue with Fishbone diagram, Root cause analysis, 8D report.

For shared records, evidence and follow-up, explore Bulk quality. Start a free trial to run it live, no card needed.