PDCA is the scientific method behind kaizen. It turns improvement ideas into experiments and keeps teams from rolling out untested fixes.
Where it comes from
PDCA builds on Walter Shewhart's cycle and was popularized in Japan by W. Edwards Deming, who later preferred the term PDSA for plan, do, study, act. Toyota made it central to its problem solving.
At a glance
The PDCA wheel
Swipe sideways to see the whole diagram.
How to apply PDCA
- 1
Plan
Define the problem, the current condition and the target. Form a hypothesis about what change will close the gap and how you will measure it.
- 2
Do
Run the change on a small scale, such as one shift or one cell. Record what actually happens.
- 3
Check
Compare results to the prediction and the baseline. Look for side effects as well as the intended gain.
- 4
Act
If the change worked, standardize it and spread it. If not, adjust the hypothesis and start another cycle.
Worked example (illustrative)
A warehouse team predicts that moving the 50 fastest-moving items closer to packing will cut walking time per pick route by at least 15%. They try it in one aisle for a week and time 40 pick routes. Average walking time falls from 6.0 to 4.8 minutes, a 20% drop, which beats the prediction, so they re-slot the remaining aisles and update the slotting rule.
Common mistakes
- Skipping the check step and treating every change as a success.
- Planning large rollouts instead of small, fast experiments.
- Not writing down a prediction, so there is nothing to learn from the results.
When PDCA is not the right tool
PDCA is for change with an uncertain outcome. Routine work that already meets its standard runs on SDCA instead: standardize, do, check, act.
It also needs a prediction. Without a stated expected result, the check step has nothing to compare against.
PDCA meaning
PDCA stands for plan, do, check, act. It is a four-step cycle for testing a change on a small scale before adopting it.
Plan the change from the cause of a problem. Do it on a small scale. Check the result against the plan. Act by adopting, adjusting or dropping the change.
PDCA cycle example
This example is illustrative. About 12% of a team's orders ship late because of missing paperwork. Plan: the team adds a checklist at order entry and predicts late orders will fall below 5%.
Do: one shift uses the checklist for two weeks. Check: late orders on that shift fall to 4%, while the other shifts stay near 12%. Act: the checklist becomes the standard for every shift.
The Deming cycle and the Shewhart cycle
The cycle grew from Walter Shewhart's work on quality in the 1920s and 1930s. W. Edwards Deming taught it in Japan from 1950, so it is often called the Deming cycle.
Deming later preferred plan, do, study, act, or PDSA. Study stresses learning from the result rather than only checking it. Toyota made the cycle central to its problem solving, and the A3 report puts one PDCA cycle on a single page.
PDCA and SDCA
SDCA keeps a process at its current standard. PDCA raises the standard. Teams move between the two: improve with PDCA, then hold the gain with SDCA.
Standard work is the S in SDCA.
PDCA in Toyota Kata
Mike Rother's book Toyota Kata describes short, repeated PDCA experiments with a coach. Each one moves a team a step toward a target condition.
A one-page PDCA log
Keep one line per cycle with five fields: the change, the prediction with a number, how you measured, the result, and the decision to adopt, adjust or drop.
For the illustrative warehouse test: re-slot the 50 fastest items in aisle 3; predict 15% less walking per route; time 40 routes over a week; walking fell 20%, from 6.0 to 4.8 minutes; adopt in all aisles.
A log like this shows which predictions were wrong, which is where the team learns most.
Guides on this topic
- Kaizen event: meaning, steps and a 3-5 day agendaA kaizen event is a focused workshop that improves one process in 3-5 days. Learn the meaning, roles, agenda, steps, measures and common mistakes.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
- Process improvement methodologies: 9 methods comparedProcess improvement methodologies compared: PDCA, lean, kaizen, Six Sigma, TQM, theory of constraints, BPR and retrospectives, with how to choose and combine.Read the guide
- Lean thinking: the 5 principles and the mindsetLean thinking is a way of creating value with less waste. Learn the five principles, the lean mindset, how it differs from lean tools and how managers apply it.Read the guide
Sources
Books and papers show their publication year. Web pages show the month we last checked them.
- 1.W. Edwards Deming, Out of the Crisis (MIT Center for Advanced Engineering Study, 1986)
- 2.Walter A. Shewhart, Economic Control of Quality of Manufactured Product (D. Van Nostrand, 1931)
- 3.Mike Rother, Toyota Kata: Managing People for Improvement, Adaptiveness and Superior Results (McGraw-Hill, 2009)