DMAIC Explained: The 5 Phases of Six Sigma Improvement

5 min read · Updated July 2026

DMAIC is the backbone of Six Sigma problem solving. It keeps teams from jumping to solutions before they understand the problem, and makes sure improvements actually stick. Here is what happens in each of the five phases.

D — Define

Agree the problem, the goal and the scope. Capture who the customer is and what "good" means to them. The key output is a short project charter everyone signs up to.

M — Measure

Quantify the current situation. Collect trustworthy data on how the process performs today so you have a baseline to improve from — you cannot improve what you have not measured.

A — Analyse

Find the real root causes, not the symptoms. Use the data and simple tools (like the 5 Whys and cause-and-effect diagrams) to separate the vital few causes from the trivial many.

I — Improve

Design, test and implement changes that address the root causes. Pilot on a small scale first, confirm the improvement with data, then roll it out.

C — Control

Lock in the gains so the problem does not creep back. Standardise the new way of working, add simple monitoring, and hand ownership to the team that runs the process.

Why the order matters

Most failed improvements skip Measure and Analyse and go straight to Improve — fixing the wrong thing, or fixing the right thing without proof. DMAIC’s discipline is exactly what makes the results reliable.