Lean teams use A3s because the one-page limit encourages clear, concise thinking. The format also makes it easy for a coach or manager to review the logic and ask good questions.
Where it comes from
A3 thinking was developed at Toyota and is named after the A3 paper size, roughly 11 by 17 inches. It follows the PDCA cycle.
At a glance
The A3 report, one page
Swipe sideways to see the whole diagram.
How to apply A3
- 1
Background
State why the problem matters to the business or the customer. Name the owner and the scope.
- 2
Current condition
Describe what is happening now with facts, charts and observations from the gemba. Avoid opinions and solutions here.
- 3
Goal
Set a specific, measurable target condition and a date. Make clear how you will know the problem is solved.
- 4
Root cause analysis
Use five whys, a fishbone diagram or Pareto charts to find the causes. Confirm them with data before moving on.
- 5
Countermeasures and plan
List actions that address each root cause, with owners and dates. Keep the plan short and testable.
- 6
Check and follow up
Track results against the goal and record what you learned. Standardize what worked and note open issues.
Worked example (illustrative)
A clinic lab relabels about 14 samples per 1,000. The A3 shows that 70% of those errors come from handwritten labels at one draw station. The team trials printed labels at that station and tracks errors for a month. The rate falls to about 5 per 1,000, so the change rolls out to the other stations.
Common mistakes
- Writing the solution in the background box and working backward to justify it.
- Filling the A3 alone at a desk instead of using it as a coaching conversation.
- Stopping at the plan and never completing the check and follow-up sections.
When A3 is not the right tool
Small problems with an obvious fix do not need an A3. A note on the team board and a quick check are enough.
An A3 is also not a form to complete alone. Without a coach or reviewer asking questions, it loses most of its value.
What is A3 problem solving?
A3 problem solving is a structured method that fits one problem onto a single sheet of A3 paper. A3 is the international paper size of 297 by 420 millimeters.
The method comes from Toyota. The sheet follows the PDCA cycle, from the background of a problem to the follow-up after the fix.
A3 report template
The left side of a typical A3 holds the background, the current condition, the goal and the root cause analysis. The right side holds the countermeasures, the plan and the follow-up.
Charts and sketches replace long text, so the sheet can be read in a few minutes. The A3 step-by-step guide walks through each box with an example.
A3 thinking
A3 thinking is the habit behind the sheet: understand the current condition before proposing a fix, and test causes with evidence.
In lean management, a coach reviews the A3 with its owner and asks questions instead of giving answers. The sheet becomes a record of how the problem was solved.
Types of A3
The problem-solving A3 is the most common. Teams also use proposal A3s to make the case for a change, and status A3s to report progress on a plan.
John Shook's book Managing to Learn describes A3 as a way for managers to coach. The reviewer asks questions at each box rather than giving answers.
A3 and PDCA
The left side of a problem-solving A3 covers Plan: background, current condition, goal and root cause. The right side covers Do, Check and Act: countermeasures, the plan, results and follow-up.
See PDCA and the A3 step-by-step guide.
A filled-in A3, one line per box
This is the illustrative lab example from above, cut to one line per box.
Background: relabeled samples delay results and risk errors, about 14 per 1,000 samples. Current condition: 70% of relabels start at draw station 3, where labels are handwritten.
Goal: under 6 relabels per 1,000 within two months. Root cause: handwriting is misread at the analyzer, and station 3 has no label printer.
Countermeasures: a printer at station 3, owned by the lab lead, trialed for one month. Plan: install in week 1, track daily relabels, review weekly.
Follow-up: the rate fell to about 5 per 1,000, so printers go to the remaining stations, and the A3 is reviewed again after three months.
Guides on this topic
- Root cause analysis example: 6 worked samples and a templateA root cause analysis example for six settings, from a machine stoppage to warehouse picking errors, plus root cause statement wording and common mistakes.Read the guide
- Lean healthcare: principles, tools and how to startLean healthcare applies lean methodology to patient care. See the principles, hospital wastes, tools, patient flow and how to start in a clinic or ward.Read the guide
- Continuous improvement in lean: examples and strategiesContinuous improvement in lean explained: the PDCA cycle, daily kaizen and kaizen events, with practical examples and strategies that keep improvement going.Read the guide
- What is a lean stack? Choosing tools by practiceA lean stack is the small set of lean tools a team uses to run its practices. How to choose lean tools and techniques without buying software you won't use.Read the guide
Sources
Books and papers show their publication year. Web pages show the month we last checked them.
- 1.John Shook, Managing to Learn: Using the A3 Management Process (Lean Enterprise Institute, 2008)
- 2.Durward K. Sobek II and Art Smalley, Understanding A3 Thinking: A Critical Component of Toyota's PDCA Management System (Productivity Press, 2008)