Value stream mapping symbols: the standard VSM icon set

Value stream mapping symbols are a small set of standard icons that show how material and information move through a process. The most widely used set comes from Mike Rother and John Shook's 1998 workbook Learning to See, published by the Lean Enterprise Institute.

Each icon answers one question. Where does work wait? What triggers the next step? Who sends the signal? With about twenty shapes you can read almost any map and draw your own.

Key takeaways

Value stream mapping icons fall into four groups: process, material, information and general.

Process boxes show where work happens, and data boxes beneath them hold the numbers.

The inventory triangle marks waiting, and the push arrow marks work pushed forward without a signal.

Kanban symbols and the supermarket show where a pull system controls flow.

The timeline at the bottom separates lead time from processing time.

What are the standard value stream mapping symbols?

The standard set is the one taught in Learning to See, and most mapping tools copy it. It is sometimes called the VSM symbol set or the value stream symbols.

Some authors and software vendors add or redraw icons, so you may see small differences. The meaning matters more than the exact shape, as long as everyone reading your map agrees on it.

Below, the symbols are grouped the way a map is read. First come who and what, then material flow, then information flow, then the extras. For the method itself, see value stream mapping.

Process symbols: customer, process box and data box

The customer/supplier symbol is a factory-shaped icon that marks where material or demand starts and ends. Draw the customer at the top right and the supplier at the top left, with the customer's demand written beneath it.

The process box is a plain rectangle that shows one step of the flow, such as welding or order entry. Draw one box for each area where material flows continuously, not for every machine.

The data box is a smaller rectangle attached under a process box. It holds the facts you collected, such as cycle time, changeover time, number of operators and uptime.

The shared process symbol is a process box with a bracket or extra frame. Use it when several value streams use the same step, such as one paint booth serving three product families.

Material symbols: inventory, push, supermarket and shipments

The inventory triangle, usually with the letter I inside, shows stock sitting between steps. Write the quantity and the time it represents beneath it, for example 2,000 pieces or 2 days of demand.

The push arrow is a striped arrow that shows material moved ahead without the next step asking for it. Draw it between processes that build to a schedule instead of a signal.

The shipment truck shows deliveries to the customer or from the supplier. The external shipment symbol, often a truck with a dotted outline, marks transport by an outside carrier. Add the delivery frequency, such as one a day.

The supermarket is an open-fronted shelf icon. It marks a controlled stock point where a downstream process takes what it needs and the upstream process refills only what was taken.

The withdrawal or pull arrow is a circled arrow that shows a downstream process taking material from a supermarket. It is the physical sign of a pull system.

The FIFO lane is a short lane with a maximum quantity written above it. Use it when two processes are linked by first-in, first-out flow with a fixed limit. The upstream step stops when the lane is full.

The safety or buffer stock symbol looks like an inventory icon with a label. Draw it where you keep extra stock on purpose to cover demand swings or breakdowns, and note how much.

Information symbols: flow, kanban and leveling

Manual information flow is a straight arrow, such as a printed schedule or a verbal instruction. Electronic information flow is a zigzag arrow, such as an order sent by EDI or an ERP release. Label each arrow with what it carries and how often.

The production kanban symbol is a card icon that tells an upstream process what to make and how much. The withdrawal kanban tells a downstream process what it may take from a supermarket. Read more on the kanban page.

The signal kanban is a triangle-shaped card used when a batch process needs a trigger. It is raised when stock falls to a set level, which tells the process to run a batch.

The kanban post is a small box or slot where cards collect. Draw it where cards are gathered before being sent back upstream.

The load leveling box, often called a heijunka box, shows where orders are sorted into an even mix over time. The production control or scheduling box, drawn at the top center of the map, shows the central group that sends schedules to each process.

The go see schedule is a small eye-glasses icon. It marks an information check that someone does by walking the floor, such as a supervisor reviewing stock levels at set times.

General symbols: kaizen burst, operator and timeline

The kaizen burst is a jagged starburst drawn on the current state map. It marks a problem that needs improvement, such as a long changeover, and the idea behind it is covered in kaizen.

Teams often turn those bursts into kaizen events. The bursts then appear on the future state map as the work to be done.

The operator symbol is a small figure drawn next to a process box. It shows how many people work there, which helps you check the work against takt time.

The timeline, sometimes called the ladder, runs along the bottom of the map. Its top rungs show waiting time and its bottom rungs show processing time.

How do you read the timeline: lead time vs processing time?

Lead time is the total time one item spends in the whole value stream. Processing time is only the time spent being worked on. The timeline shows both side by side.

Say a part waits 3 days before a press and takes 40 seconds to press. It then waits 2 days before assembly and takes 60 seconds to assemble. Lead time is about 5 days. Processing time is 100 seconds.

The gap is mostly inventory waiting between steps, so improvement usually starts there.

To convert inventory into days, divide the quantity in the triangle by daily customer demand. Illustratively, 2,000 pieces at 1,000 per day is 2 days.

A small example map, described in words

Picture a simple three-step stream: stamping, welding and assembly. The customer sits at the top right and the supplier at the top left, with a production control box at the top center.

A zigzag arrow runs from the customer to production control for the electronic order. A manual arrow carries the weekly schedule from production control to each process.

Between stamping and welding sits an inventory triangle marked 2 days. A striped push arrow joins stamping to it, because stamping builds to its own schedule.

Welding and assembly are joined by a FIFO lane with a maximum of 50 pieces. Under each process box is a data box with its cycle time and operator count.

At the bottom, the timeline lists the waiting days and processing seconds. A kaizen burst over stamping marks a long changeover as the first problem to attack.

Drawing symbols by hand or in software

Draw by hand first when you are learning the current state. Pencil, paper and sticky notes let you walk the floor, correct the map and involve the people who do the work. The paper-first guide explains why.

Keep the symbols simple on paper. A triangle with an I, a box with data lines and a zigzag arrow are enough. The team only needs to agree on the key.

Move to software when the map must be shared, versioned or compared with a future state. Look for a tool that includes the standard icon set, so you are not redrawing shapes. The value stream mapping software category lists options.

Whatever you use, include a legend and keep the symbols the same on every map in your company. Consistency lets a new reader follow the map quickly.

Frequently asked questions