What is a SIPOC diagram?
A SIPOC is a one-page table that shows a process at a high level, along with everything that flows into it and out of it. The name is the five columns:
| Letter | Column | Question it answers |
|---|---|---|
| S | Suppliers | Who provides what the process needs? |
| I | Inputs | What goes into the process: material, information, equipment, people? |
| P | Process | What are the 4–7 main steps, from start to end? |
| O | Outputs | What comes out: product, records, and waste too? |
| C | Customers | Who receives each output, inside or outside the company? |
That's it. A SIPOC doesn't show decisions, loops or every little task. Its job is to get everyone looking at the same process, with the same start and end, before a project goes any further.
When to use a SIPOC
The SIPOC's home is the Define phase of DMAIC. It sits alongside the project charter and does three things there:
- Sets the scope. The start and end points make "in scope" and "out of scope" concrete. If a step isn't between them, it isn't in the project.
- Names the customers. You can't define what "good" looks like until you know who receives the output, and internal customers count.
- Shows where to measure. The outputs (and their requirements) point to the measures you'll collect in the Measure phase. The inputs point to likely causes later in Analyze.
It's also useful outside DMAIC: before a detailed process map, when onboarding someone to a process, or before a 5S or kaizen event so the team agrees on the boundaries.
How to build a SIPOC in 7 steps
Fill it in from the middle out. Starting with the process and then the customer side keeps the team focused on what the process actually delivers.
- Name the process and set the boundaries. Write one line for where it starts ("a released work order reaches the cell") and one for where it ends ("packed parts are handed to the warehouse"). Agree on these with the process owner.
- Process: list 4–7 high-level steps. Use verb + noun: "Set up machine," "Inspect parts." If you have 15 steps, combine them; the detail goes in a process map later.
- Outputs: list what the process produces. Include the product, but also records, information and waste (scrap, rework). They all go somewhere.
- Customers: list who receives each output. The next department is a customer. So is quality, if they receive your inspection records.
- Inputs: list what the process needs. Material, information (orders, drawings, programs), equipment, gauges and trained people.
- Suppliers: list who provides each input. Internal suppliers (stores, engineering, the tool crib) count just like outside vendors.
- Add requirements, then review. Where you can, write what customers need from each output and what the process needs from each input (spec, quantity, timing). Review it with people who run the process, then attach it to the charter.
A worked example
Here's a SIPOC for a DMAIC project on late orders at a CNC machining cell. This example is illustrative, made up to show the method, not real data.
| S · Suppliers | I · Inputs | P · Process | O · Outputs | C · Customers |
|---|---|---|---|---|
| Production control | Released work order (part no., qty, due date) | Review work order and pull material | Finished brackets | Assembly line (internal) |
| Stores / steel supplier | Aluminum bar stock | Set up machine and load program | Inspection records | Quality department |
| Engineering | Drawing (current rev) and CNC program | Run first piece and get approval | Labeled boxes and packing list | Warehouse / shipping |
| Tool crib | Cutting tools and fixtures | Machine the order | Scrap and rework tags | Material review / quality |
| Metrology | Calibrated gauges | Inspect parts in process and at end | Completed work order | Production control |
| Training | Trained machinist | Deburr, count and pack | ||
| Hand packed order to warehouse |
Three things to notice:
- Information is an input. The work order, the drawing revision and the CNC program matter as much as the bar stock. On a "late orders" project, a late or wrong work order is a likely suspect.
- Waste and records are outputs. Scrap and rework tags go to quality; the completed work order goes back to production control. Leaving them off hides part of the process.
- The columns don't line up one-to-one. That's fine. A SIPOC is five lists, not a grid of matched pairs.
The same example, with input and output requirements filled in, is on the "Example" tab of the free template.
Common SIPOC mistakes
- No start and end point. Without boundaries the SIPOC can't set the scope, and the project quietly grows.
- Too much detail. 20 process steps with decision diamonds is a process map. Keep a SIPOC to 4–7 steps.
- Only physical inputs. Orders, drawings, programs, instructions and training are inputs too, and they cause a lot of problems.
- Forgetting internal customers. The next operation is usually the customer who feels a problem first.
- Built by one person at a desk. The people who run the process know the inputs and handoffs that never make it into procedures.
- Made once for the slide deck. If the scope changes during the project, update the SIPOC and the charter together.
SIPOC questions people ask
What does SIPOC stand for?
Suppliers, Inputs, Process, Outputs, Customers. It's a one-page, high-level view of a process and everything that flows into and out of it.
When should I use a SIPOC?
Most often in the Define phase of a DMAIC project, to agree on the scope of the process before you measure anything. It's also useful any time a team needs a shared picture of a process, for example before a process map, a value stream map or a kaizen event.
How many process steps should a SIPOC have?
Keep it high level: about 4 to 7 steps. If you need more, you're drawing a detailed process map, which is a different tool.
Which order do you fill in a SIPOC?
Most teams start in the middle: set the start and end points, list the Process steps, then Outputs and Customers, then Inputs and Suppliers. Starting from the customer side keeps the focus on what the customer actually receives.
What is the difference between SIPOC and COPIS?
They hold the same information. COPIS is SIPOC read backwards (Customers, Outputs, Process, Inputs, Suppliers) and is used to stress starting from the customer.
What is SIPOC+R?
A SIPOC with an extra row or columns for requirements: what customers need from each output and what the process needs from each input. It links the SIPOC to voice of the customer and critical-to-quality (CTQ) requirements.
