Where the A3 comes from
The A3 format grew out of Toyota's practice of summarising problems and proposals on a single sheet of A3 paper. The constraint is deliberate. Fitting everything on one page forces the author to understand the problem deeply and to communicate only what matters. The A3 is as much a coaching tool as a report: a manager reviews it with the author and asks questions until the logic holds.
The standard sections
Formats vary, but most problem-solving A3s follow the PDCA cycle from left to right:
| Section | What it answers |
|---|---|
| Background | Why does this problem matter now? |
| Current state | What is actually happening, with facts and data? |
| Goal or target state | What does good look like, and by when? |
| Root cause analysis | Why is there a gap between current and target? |
| Countermeasures | What will we change to address the root cause? |
| Implementation plan | Who does what, by when? |
| Follow-up | How will we check it worked, and what did we learn? |
The left side covers Plan. The right side covers Do, Check and Act.
How to use an A3 well
- Write it in pencil, figuratively and sometimes literally. Expect several revisions.
- Fill in the current state at gemba, with charts and sketches rather than paragraphs.
- Keep the problem statement free of solutions.
- Review it with a coach or the problem owner's manager at each stage.
- Use it to brief stakeholders and build agreement before acting.
Common mistakes
- Treating the A3 as a form to complete after the decision has already been made.
- Skipping straight from current state to countermeasures without verified causes.
- Crowding the page with text instead of visuals.
- Never filling in the follow-up section, so nobody checks whether the countermeasures held.
Example
A warehouse team sees pick errors rising. Their A3 shows the trend, maps where errors occur, and uses a fishbone and 5 whys to trace most errors to similar-looking products stored side by side. Countermeasures re-slot those items and add location labels. The follow-up section tracks errors weekly and records the new slotting rule as standard work.