A3 problem solving: the method and the report

What is A3 problem solving?

A3 problem solving is a Lean method for working through a problem in a structured way and telling the whole story on a single sheet of A3 paper. It came from Toyota, where a report that didn't fit one page was taken as a sign that the thinking wasn't finished yet.

The page is not the point — the discipline is. An A3 forces you to describe what is actually happening before proposing what to change, to show the reasoning behind a root cause, and to name a measure that tells you whether the change worked.

• One page forces clarity — if it doesn't fit, the thinking isn't finished.
• Understand the current condition before proposing a countermeasure.
• Go and see the real work (Gemba); don't solve from a meeting room.
• Find root causes with 5 Whys or a fishbone, not the first plausible answer.
• Countermeasures are experiments with owners, dates, and a measure.
• The A3 is a conversation, not a form to file.

The A3 report structure

The sheet is read left to right. The left column covers the problem and its causes; the right column covers what you will do about it and what happened.

1. 1. Background

   Why this problem matters now, in one short paragraph. Tie it to a customer, a cost, or a strategic goal so the reader knows why to spend time on it.

2. 2. Current condition

   What is actually happening today, with facts and a simple picture — a process sketch, a chart, or the numbers. This is usually the hardest half of the page and the part people skip.

3. 3. Goal / target condition

   The measurable state you want, with a date: "first response under four hours by 30 November", not "improve responsiveness".

4. 4. Root cause analysis

   Why the gap exists. Use 5 Whys or a fishbone diagram and show the reasoning, so the reader can challenge it rather than just accept it.

5. 5. Countermeasures

   The changes you will test against each root cause. Call them countermeasures, not solutions — it keeps them provisional and testable.

6. 6. Implementation plan

   Who does what, by when. A short table of actions, owners, and dates is enough.

7. 7. Follow-up and results

   What happened to the measure, what you learned, and what becomes the new standard. An A3 without this section is a proposal, not problem solving.

Sections 1–4 are the Plan of a PDCA cycle; sections 5–7 are Do, Check, and Act.

How to run an A3, step by step

1. 1. Agree the problem with the owner

   Write the problem as a gap between what should happen and what does. If two people describe it differently, stop and align before going further.

2. 2. Grasp the current condition at the Gemba

   Walk the process with the people who do it, and map the steps and the waiting between them. Bring back facts, not impressions.

3. 3. Set a target condition with a number and a date

   A target without a measure can't be checked, so the A3 never closes.

4. 4. Dig to root causes

   Ask why until you reach something you can actually change. Three to five layers is typical; stopping at the first layer produces cosmetic fixes.

5. 5. Test countermeasures in small cycles

   Run each one as a PDCA cycle on a limited scale, then check the measure before rolling it out.

6. 6. Standardise what worked and share the A3

   Update the standard way of working, then keep the A3 visible — most of its value is in what other teams learn from it.

Step 2 is much easier with a map of the process: how to create a process map.

A worked example

Background: customer invoices are disputed often enough that finance spends a day a week on corrections. Current condition: of 280 invoices last month, 34 were disputed; 27 of those were missing a purchase-order reference.

Target: disputes under 5% of invoices within two months. Root cause (5 Whys): the PO reference is optional in the order form, because it isn't known at the time sales creates the order.

Countermeasures: make the field required before invoicing rather than at order entry, and add a weekly check on orders still missing it. Follow-up: disputes fell to 11 the following month; the check became part of the standard weekly routine.

Common mistakes

• Jumping to the countermeasure box and back-filling the analysis.
• A current condition made of opinions instead of observed facts.
• Targets with no number or no date, so nobody can tell whether it worked.
• Treating the A3 as a template to complete rather than thinking to do.
• Writing it alone — an A3 is a coaching dialogue between owner and mentor.
• Never returning to the follow-up section once the change is made.

How FollowLean fits

FollowLean keeps the A3 attached to the work it describes: the current condition is the process map itself, root causes and countermeasures sit on the exact steps they belong to, and each countermeasure runs as a PDCA cycle with an owner, a date, and a measure — so the follow-up section actually gets filled in.

FAQ

What does A3 mean in Lean?

A3 refers to the international paper size (297 × 420 mm) that Toyota used for problem-solving reports. The constraint is the point: the whole story — background, current condition, analysis, countermeasures, and results — must fit on a single sheet, which forces the thinking to be clear.

What are the sections of an A3 report?

Most A3s use seven sections: background, current condition, goal or target condition, root cause analysis, countermeasures, implementation plan, and follow-up with results. Variants exist, but the left-to-right flow from problem to plan is always the same.

How is A3 different from PDCA?

They are the same logic in different forms. PDCA is the improvement cycle; the A3 is the one-page way of documenting and coaching a PDCA cycle. The left side of the A3 is Plan, and the right side is Do, Check, and Act.

When should I use an A3 instead of a quick fix?

Use an A3 when the problem is recurring, the cause is unclear, or several teams are involved. For an obvious, cheap fix, just make the change — writing an A3 for it is waste.

How long does an A3 take?

Days to weeks, not hours. Most of the time goes into understanding the current condition and testing countermeasures; the writing itself is quick once the thinking is done.