KaizumiKaizumi™

5 Whys

Root cause analysis · reasoning checked

1/3

Five whys is a ladder, not a quiz

Each rung has to cause the one above it. Read it back upward — "this, therefore that" — and if that sentence does not hold, neither does the ladder. Five is a rule of thumb: stop when you reach something you can go and change.

Every industry carries two chains for the same problem — a strong one and a weak one. Load each and press "Review my thinking" to see what separates them.
The problem
1
Why did that happen?
2
And why did that happen?
3
And why did that happen?
4
And why did that happen?
Root cause
Countermeasure
Your chain is read back one rung at a time — which links hold, which stop at a person or a fix, and whether the countermeasure reaches the root.

Want an editable copy?

A printable 5 Whys sheet with the problem, five why rows, root cause, countermeasure, and owner — ready for your next problem-solving session.

What is the 5 Whys method?

The 5 Whys is a root cause analysis technique: state a problem, then ask “why did that happen?” repeatedly, using each answer to drive the next question. Five is a rule of thumb, not a rule — some chains resolve in three whys, others need seven. The point isn’t the count; it’s reaching something concrete enough to go and change, rather than stopping at the first plausible-sounding excuse. For the full method and worked example, see the 5 Whys field guide.

Where chains usually break

Most 5 Whys chains fail quietly, and almost always one of four ways. A rung can blame a person instead of naming a condition of the system. A rung can be a countermeasure in disguise— “needs a checklist” is something to do, not something that was wrong. A rung can be too abstract to go and see — a culture or an attitude nobody can observe or measure directly. Or the causal link can simply not holdwhen you read it back upward: “this, therefore that.” Left unchecked, a chain like that bottoms out in a root cause nobody could actually go and change. The review panel names which one applies to each rung you write.

How to use this tool

Start from one of the loaded examples — manufacturing, healthcare, warehouse, or office — or clear the form and write your own problem. Add or remove why rows as your chain needs, fill in the root cause and countermeasure you landed on, then click Review my thinking. You’ll get a verdict on every rung, a check on whether a 5 Whys is even the right instrument for this problem, a read on whether your root cause is actionable, and one probing question to take back to the floor.

Common questions

What is the 5 Whys method?
The 5 Whys is a root cause analysis technique: state a problem, then ask "why did that happen?" repeatedly, using each answer to drive the next question. The aim is to move past the first plausible-sounding explanation and reach a condition concrete enough that you could go and change it.
How many whys should you ask?
As many as it takes, and no more. Five is a rule of thumb rather than a rule — some chains reach something you can act on in three, others need seven. Counting to five and stopping is how chains end on an answer nobody can do anything with. Stop when you reach a condition you could go and change.
When is a 5 Whys the wrong tool?
A 5 Whys is built for a gap from a known standard — something that used to work, or should work, and does not. It is the wrong instrument for three other kinds of problem: troubleshooting, where you just need the process running again now; a target condition, where you are raising performance beyond the current standard rather than repairing a break; and an open-ended problem with no standard to gap against. Asking "why" of a target you have never hit tends to walk backwards until it finds a decision someone made, which is a different exercise entirely.
Why is "nobody was trained" not a root cause?
Because it is a procedural gap, not a mechanism. "It was not in the standard", "there was no procedure" and "nobody was trained" all describe something missing from the paperwork rather than what made the failure possible — and standardising the fix is the countermeasure, not the cause. A real root cause is technical or physical: something about the equipment, the material, the layout, the timing, or the information flow. If a chain bottoms out in a training gap, there is usually one more why underneath it.
What is the difference between a root cause and a countermeasure?
A root cause is what was wrong; a countermeasure is what you will do about it. Chains often blur the two by writing a rung as an action — "needs a checklist", "should add a second check" — which tells you the fix you already had in mind rather than the condition that caused the problem. A useful test: a countermeasure should be answerable to the question "how would this change the root cause?" If it cannot be traced to the root, it is aimed at a symptom.
Does this tool store the problems I write?
No. The chain lives in your browser for as long as the page is open and is not saved to an account or a database. The text is sent to the review model only when you press Review my thinking, and nothing is retained afterwards.

Related tools