Operations & process
SIPOC
A one-page map of a process in five columns: Suppliers, Inputs, Process, Outputs, Customers. Built at the start of an improvement effort, it fixes the scope and boundaries before anyone argues about detail, and exposes who the process actually depends on and serves.
Also known as SIPOC diagram, COPIS, High-level process map. First set out by No single originator; codified in the total quality management and Six Sigma toolkits in 1990; the primary source is cited in full below.
Where this is contested
SIPOC has no single credited inventor. It appears in total quality management practice from the late 1980s and was standardised through the Six Sigma programmes at Motorola and General Electric in the 1990s; the year given is indicative of that period.
- Format
- Mapping
- Level
- Business unit · Team
- Best for
- Structure the problem
- Decision stage
- Diagnose · Plan
- Difficulty
- Introductory
- Time to apply
- A one-hour workshop for a first pass; a short validation round after.
Plate · The model
The components
Suppliers
The people, organisations or systems that provide the process with its inputs, internal as much as external. The column makes visible whose performance the process is hostage to, which is often the improvement project's real territory.
Signals of strength
Every input has a named supplier · Internal suppliers listed alongside vendors · Customers who also supply inputs are flagged · Unmanaged suppliers marked for the risk log
Inputs
What the process consumes to work: materials, parts, information, specifications, authorisations. Input quality bounds output quality, so this column is where upstream causes of downstream defects first appear on paper.
Signals of strength
Materials and information both captured · Requirements for critical inputs stated · Inputs with no acceptance check highlighted · Missing or late inputs noted as known pain
Process
The four to seven high-level steps between trigger and end point. The discipline is altitude: enough structure to agree scope and place measurements, too little to start solutioning.
Signals of strength
Clear start and end events · Four to seven steps, each verb plus noun · Steps describe what happens today, not the ideal · Agreed by the people who run it
Outputs
Everything the process produces: the intended products and services, plus by-products such as rework, waste, records and certificates. Unflattering outputs belong on the map, because they are usually why the project exists.
Signals of strength
Primary outputs and by-products both listed · Each output traceable to a customer or a bin · Defective output streams quantified where known · Measurable characteristics identified for key outputs
Customers
Whoever receives each output: external clients, their end users, internal next-step teams, regulators. Attaching requirements to customers turns the map from a diagram into a definition of what good means for this process.
Signals of strength
Internal and external customers distinguished · Requirements captured in the customer's terms · Conflicting requirements between customers surfaced · The customer whose complaint triggered the project identified
When it earns its keep
- You are launching a process-improvement project and need the team, the sponsor and the process owner to agree what the process is before anyone proposes fixing it.
- A DMAIC project is in its Define phase and the charter needs defensible start and end points; SIPOC is the standard opening move.
- A process crosses departments and each group holds a different mental map of where it begins, what it needs and who it serves.
- You suspect a quality problem originates upstream of the process being blamed, and want the supplier and input columns to make that discussable.
And when it doesn't
- You already need step-level detail: cycle times, queues, rework loops. SIPOC deliberately stays at four to seven steps; move to value-stream mapping or a service blueprint for the mechanics.
- The problem is a single known defect with a known location. Go straight to root-cause tools such as five whys or a fishbone diagram.
- The 'process' is genuinely ad hoc knowledge work with no repeatable flow. Forcing it into five columns produces a tidy fiction.
- You want the map to persuade rather than describe. A SIPOC drawn to justify a predetermined scope will be contradicted by the first person who actually runs the process.
How to run it
Before starting, gather the inputs the analysis depends on:
- A named process with a working definition of its trigger and end point.
- People who operate the process day to day, not just those who manage it, in the room for the mapping session.
- Knowledge of who supplies each input and who receives each output, including the internal ones nobody invoices.
- The customer requirements for the key outputs, even in rough form, so the map connects to what matters.
- 1
Name the process and fix its boundaries
Agree the trigger that starts the process and the event that ends it. Most SIPOC arguments are boundary arguments in disguise, and settling them first is the tool's main contribution to a project charter.
- 2
Map the process in four to seven steps
Fill the middle column first, at deliberately high level. If the team produces fifteen steps, the boundaries are wrong or the altitude is; SIPOC describes the flight path, not the wiring.
- 3
List outputs, then customers
Record what the process produces, including unintended outputs such as scrap, effluent and paperwork, then name who receives each one. Attach the customers' requirements to the key outputs; some practitioners work this direction first and call the result COPIS to keep the customer in charge.
- 4
List inputs, then suppliers
Record what the process consumes, materials, information and specifications, and who provides each. This column routinely produces the project's first discovery: inputs nobody controls and suppliers nobody manages.
- 5
Validate and put it to work
Walk the finished page past people who run the process and at least one customer, then use it to set the improvement charter's scope, the measurement points and the stakeholders. A SIPOC that goes into a slide deck and never constrains the project was decoration.
Reading the result
A single-page, validated map of the process at high altitude: its boundaries, its four to seven steps, what it consumes and from whom, what it produces and for whom, with customer requirements attached. It becomes the scope section of the improvement charter.
- Read it as a boundary document first. Anything outside the start and end events is out of scope until the team deliberately decides otherwise.
- Read across rows for trouble: an input with no acceptance check, a supplier nobody manages, an output with no named customer. The blank cells are the findings.
- Read the customer column against the output column to locate measurement. Where a requirement meets an output is where the project's baseline metrics belong.
A worked example
A powder-coating plant scopes its rework problem
A Midlands industrial powder-coating plant applies finishes to fabricated steel parts for trade customers. Rework is running at 9% of throughput and the coating line crew is being blamed. Before launching a defect-reduction project, the operations manager runs a one-hour SIPOC session with the line lead, the goods-in operator, the sales administrator and a maintenance fitter, mapping the process from 'customer parts arrive' to 'coated parts despatched'.
- Suppliers
- Powder manufacturers, the pre-treatment chemical supplier, the jig fabricator, and, awkwardly, the customers themselves, who supply the parts to be coated. The session's first shock is on the page within minutes: the plant's most important supplier is its customer, and nobody manages that supply.
- Inputs
- Fabricated parts in variable condition, polyester powder, pre-treatment chemicals, hanging jigs, and the works order specifying colour, finish and film thickness. Parts frequently arrive with oil residue and laser scale, and there is no documented acceptance standard at goods-in; contaminated parts go straight onto the line.
- Process
- Six steps: receive and book in, load onto jigs, pre-treat and rinse, dry, apply powder and cure, inspect and pack. The team initially produced fourteen steps and was pushed back up to altitude; the detail is parked for the Measure phase.
- Outputs
- Coated parts, conformance certificates, and the unflattering by-products: rejected parts for stripping and recoating, oversprayed powder, and spent pre-treatment effluent under an environmental permit. Rework is listed as an output in its own right, which reframes it from a crew failing to a process product.
- Customers
- Trade fabricators, their end clients whose warranty claims flow back up the chain, the despatch team as internal customer of inspection, and the environmental regulator as recipient of effluent returns. Requirements captured: film thickness to specification, colour match, five-day turnaround, zero visible defects on face surfaces.
The read. The map moved the project's scope upstream: the charter now starts at goods-in rather than at the coating booth, and the first improvement action is an incoming-part acceptance standard agreed with the three largest customers. The honest reading is that SIPOC did not find the root cause, and 9% rework may yet have several parents on the line itself. What it did was stop the project from optimising the wrong boundary, and it took an hour.
Pitfalls
- Descending into detail. Fifteen process steps and sub-branches defeat the purpose; SIPOC exists to agree the whole at a glance, and detail belongs to later tools.
- Mapping the process as it is supposed to run rather than as it runs. The gap between the two is often the project, and only the day-to-day operators can tell you.
- Omitting unflattering outputs. Scrap, rework, effluent and complaints are outputs; leaving them off produces a brochure, not a map.
- Forgetting internal customers and suppliers. Most handover failures are internal, and a SIPOC that only lists external parties hides them.
- Filing the diagram once the charter is signed. Its job is to police scope for the life of the project; a SIPOC nobody re-reads was a ritual.
What the critics say
SIPOC belongs to a Six Sigma toolkit that scholars have found loosely specified: de Koning and de Mast's reconstruction of the DMAIC 'cookbook' concluded its methods are described mainly by example, with ambiguous definitions and little explicit rationale, so what a good SIPOC is, and what it validly licenses you to conclude, rests on practitioner convention rather than tested method.
de Koning, H. and de Mast, J. (2006) 'A rational reconstruction of Six-Sigma's breakthrough cookbook', International Journal of Quality and Reliability Management, 23(7), 766-787.
The linear supplier-to-customer chain embeds a goods-dominant view of value that service research has spent two decades dismantling: Vargo and Lusch's service-dominant logic holds that customers co-create value inside the process rather than receiving it at the end, so for services, and for any operation where the customer supplies the inputs, the five columns misdescribe the system they map.
Vargo, S. L. and Lusch, R. F. (2004) 'Evolving to a new dominant logic for marketing', Journal of Marketing, 68(1), 1-17.
Sources and further reading
- Pyzdek, T. and Keller, P. (2014) The Six Sigma Handbook, 4th edn. New York: McGraw-Hill.
- George, M. L. (2002) Lean Six Sigma: Combining Six Sigma Quality with Lean Speed. New York: McGraw-Hill.
- iSixSigma, 'SIPOC (Suppliers, Inputs, Process, Outputs, Customers)'. ↗
- de Koning, H. and de Mast, J. (2006) 'A rational reconstruction of Six-Sigma's breakthrough cookbook', International Journal of Quality and Reliability Management, 23(7), 766-787. ↗