How to Write an A3
- timothyferguson1
- Jun 13
- 4 min read
June 13, 2026
The A3 is deceptively simple: a single sheet of paper (originally A3-size, hence the name) that tells the whole story of a problem and its solution. That constraint is the point — if it doesn’t fit on one page, you don’t understand it well enough yet. This guide walks through the A3 section by section, with an example and a free template.
Where the A3 fits in the bigger picture: see our Complete Guide to Root Cause Analysis. https://www.fsquaredconsultinggroup.com/post/root-cause-analysis-guide
What is an A3 report?
An A3 report is a structured, one-page document that walks through a problem and its resolution using the PDCA cycle — Plan, Do, Check, Act. It comes from the Toyota Production System and is now a Lean staple for problem-solving, proposals, and status reviews. Its value is twofold: the discipline of fitting everything on one page forces clear thinking, and the shared format makes it easy for anyone to follow.
An A3 is the documentation and alignment layer of an investigation — you fill it in after (or alongside) the analysis work of defining the problem, exploring causes, and drilling to the root.
The sections of an A3 (PDCA)
A3 layouts vary, but a problem-solving A3 generally flows left to right, top to bottom, through these sections:
Plan 1. Title & header — a clear title, plus owner, team, date, and scope. 2. Problem / Need — what’s wrong, for whom, and the gap vs. the goal. (This is your problem statement.) 3. Background — context: why this matters now, how the process works today, volumes. 4. Current situation — the current state with data; a photo or chart helps. 5. Goal / Target — the measurable target condition you’re aiming for. 6. Root cause analysis — the causes you found (pull in your fishbone and 5 Whys).
Do 7. Countermeasures / Plan — the specific actions to address the root cause, with owners and dates.
Check 8. Results / Check — what actually happened after implementation, vs. the target.
Act 9. Follow-up / Standardize — how you’ll sustain the fix (standard work, audits) and what’s next. 10. Reflections — what you learned, including what you’d do differently.
How to write each section well
• Problem / Need: state it factually and measurably — no cause, no solution. How to write a problem statement. https://www.fsquaredconsultinggroup.com/post/how-to-write-a-problem-statement
• Background & current state: give just enough context for an outsider to follow; use a chart or photo instead of a paragraph where you can.
• Root cause: don’t just assert it — show the logic. Reference the fishbone. https://www.fsquaredconsultinggroup.com/post/how-to-make-a-fishbone-ishikawa-diagram-step-by-step and 5 Whys. https://www.fsquaredconsultinggroup.com/post/5-why-examples-and-a-free-template that got you there.
• Countermeasures: each one specific, owned, and dated, and clearly tied to the root cause — not the symptom.
• Results: real numbers against the target. If it didn’t work, say so — an honest A3 is more useful than a flattering one.
• Reflections: the section people skip and shouldn’t; it’s where the organization actually learns.
A short worked example
• Title: Reduce Line 3 carton seal defects · Owner: J. Smith · [date]
• Problem: ~6% of Line 3 cartons ship with unsealed top flaps since the May changeover (target <1%); causing rework and two missed shipments.
• Background: Line 3 reconfigured in May; one assembler at current demand; sealer is shared across the family.
• Current state: defect rate 6%, ~2 hrs/day rework.
• Target: <1% unsealed within 30 days.
• Root cause: No ownership of standard work → no changeover standard including sealer warm-up (from 5 Whys).
• Countermeasures: assign standard-work owner (J.S., wk 1); write changeover standard with warm-up step (wk 2); add first-article check (wk 2).
• Results: defect rate 6% → 0.7% over four weeks; rework down ~90%.
• Act / reflect: roll the standard to Lines 1–2; audit monthly; learned that “operator error” was really a missing standard.
Tips for a strong A3
• One page, really. If it overflows, tighten — don’t shrink the font to 6pt.
• Tell a story left to right. A reader should follow the logic without you narrating it.
• Show, don’t tell. Charts, a fishbone thumbnail, before/after photos beat paragraphs.
• Keep it living. An A3 evolves as the work does; it’s a thinking tool, not a final report you write at the end.
Build one free: The F Squared A3 tool gives you a structured, printable one-page A3 that pulls in your fishbone and 5 Whys, with a quick-start scaffold so you’re not staring at a blank page. Try it free →
Prefer paper? The free RCA Starter Kit includes a printable A3 template.
Frequently asked questions
What does “A3” mean?
It refers to the A3 paper size (about 11×17 inches) the report traditionally fits on. The one-page constraint is central to the method — it forces concise, clear thinking.
What are the main sections of an A3 report?
Title/header, problem/need, background, current state, goal/target, root cause analysis, countermeasures, results, and follow-up/reflections — organized around the PDCA cycle.
When should I use an A3?
To document and communicate a problem-solving effort, get a countermeasure approved, or run a structured improvement — especially when you need stakeholder alignment and a lasting record.
Do I fill in the A3 before or after the analysis?
Alongside and after. The A3 captures the problem definition, the cause analysis (fishbone, 5 Whys), and the plan — so do the analysis, then tell its story on the A3.
A3 vs. fishbone vs. 5 Whys — what’s the difference?
The fishbone explores causes, the 5 Whys drills to the root, and the A3 documents and standardizes the whole story on one page.
https://www.fsquaredconsultinggroup.com/post/fishbone-vs-5-whys-vs-a3-when-to-use-each
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