What is the Five Whys technique?

The Five Whys is a root cause analysis technique developed by Sakichi Toyoda and refined within the Toyota Production System. By repeatedly asking 'Why?' — typically five times — you trace a problem back to its fundamental root cause rather than treating its symptoms.

When should you use the Five Whys method?

Use Five Whys when a problem keeps recurring, when current fixes only treat symptoms, or when a team needs to align on the real cause of an issue. It is widely used in lean manufacturing, agile retrospectives, DevOps incident post-mortems, and quality management.

Does Five Whys have to be exactly five questions?

'Five' is a rule of thumb, not a strict limit. You stop asking why when you reach a root cause you can actually act on and fix. This might take three iterations or seven, depending on the complexity of the problem.

What is the difference between Five Whys and a fishbone diagram?

Five Whys follows a single chain of cause-and-effect, making it fast and focused — ideal for straightforward problems. A fishbone diagram (Ishikawa diagram) maps multiple potential causes across categories simultaneously, which suits more complex problems with many possible contributing factors.

Is the FiveWhys tool free to use?

Yes. FiveWhys is completely free, requires no sign-up, and runs entirely in your browser. Your analysis is saved locally in your browser and you can export it as a PNG image or download it as a file.

About FiveWhys

FiveWhys is a free, browser-based tool for running a Five Whys root cause analysis. Build a visual tree of causes, export your findings, and save your work — no sign-up, no ads, no cost.

What FiveWhys does

Most recurring problems have a surface symptom and a hidden root cause. Patching the symptom only delays the next occurrence. The Five Whys technique fixes that by walking a chain of “why” questions until you reach a cause you can actually act on.

FiveWhys turns that process into an interactive visual tree. You type your problem at the top, then add “why” nodes beneath it. The tool lays everything out automatically so you can see the causal chain at a glance — useful both for solo analysis and for presenting findings to a team.

Who uses it

Five Whys was refined inside the Toyota Production System in the 1950s, but the technique has long since spread into every discipline that cares about quality and reliability:

Software & DevOps teams — post-incident reviews (post-mortems) after production outages
Agile & product teams — retrospectives to diagnose why a sprint or feature underperformed
Manufacturing & operations — tracing defects and process failures back to their source
Quality management — satisfying ISO, Six Sigma, and lean methodologies that require documented root cause analysis
Managers & individuals — thinking clearly about any problem that keeps coming back

How it works

Open the tool, describe your problem, and click + Why to add the first cause. Keep adding causes beneath each one until you reach a root cause — something systemic you can fix. When you’re done you can:

Export as PNG — share a snapshot with your team or attach it to an incident report
Save as a file — download a .yyyyy file and reopen it later to continue the analysis
Switch themes — Daylight, Midnight, Forest, and Sunset colour palettes

Everything runs in your browser. Nothing is sent to a server or stored in the cloud.

Learn more about the Five Whys technique

The articles below go deeper into the method itself — how it works, when to use it, and real-world examples you can adapt.