Flowcharts Syntax

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Flowcharts Syntax

Flowcharts are composed of nodes (geometric shapes) and edges (arrows or lines). The Mermaid code defines how nodes and edges are made and accommodates different arrow types, multi-directional arrows, and any linking to and from subgraphs.

This page is a reference for the Mermaid syntax for flowcharts. For a more detailed explanation of the syntax, visit the official Mermaid documentation.

A node (default)

---
title: Node
---
flowchart L
    id


flowchart LR
    id

A node with text

It is also possible to set text in the box that differs from the id. If this is done several times, it is the last text found for the node that will be used. Also if you define edges for the node later on, you can omit text definitions. The one previously defined will be used when rendering the box.

---
title: Node with text
---
flowchart LR
    id1[This is the text in the box]


flowchart LR
    id1[This is the text in the box]

Unicode text

Use " to enclose the unicode text.

flowchart LR
    id["This ❤ Unicode"]


flowchart LR
    id["This ❤ Unicode"]

Markdown formatting

Use double quotes and backticks "` text `" to enclose the markdown text.

%%{init: {"flowchart": {"htmlLabels": false}} }%%
flowchart LR
    markdown["`This **is** _Markdown_`"]
    newLines["`Line1
    Line 2
    Line 3`"]
    markdown --> newLines


flowchart LR
   A -- text --> B -- text2 --> C

Direction

This statement declares the direction of the Flowchart.

This declares the flowchart is oriented from top to bottom (TD or TB).

flowchart TD
    Start --> Stop


flowchart LR
    Start --> Stop

This declares the flowchart is oriented from left to right (LR).

flowchart LR
    Start --> Stop


flowchart LR
    Start --> Stop

Possible FlowChart orientations are:

TB - Top to bottom
TD - Top-down/ same as top to bottom
BT - Bottom to top
RL - Right to left
LR - Left to right

Node shapes

A node with round edges

flowchart LR
    id1(This is the text in the box)


flowchart LR
    id1(This is the text in the box)

A stadium-shaped node

flowchart LR
    id1([This is the text in the box])


flowchart LR
    id1([This is the text in the box])

A node in a subroutine shape

flowchart LR
    id1[[This is the text in the box]]


flowchart LR
    id1[[This is the text in the box]]

A node in a cylindrical shape

flowchart LR
    id1[(Database)]


flowchart LR
    id1[(Database)]

A node in the form of a circle

flowchart LR
    id1((This is the text in the circle))


flowchart LR
    id1((This is the text in the circle))


flowchart LR
    id1>This is the text in the box

Currently only the shape above is possible and not its mirror. This might change with future releases.

A node (rhombus)

flowchart LR
    id1{This is the text in the box}


flowchart LR
    id1{This is the text in the box}

A hexagon node

flowchart LR
    id1{{This is the text in the box}}


flowchart LR
    id1{{This is the text in the box}}

Parallelogram

flowchart TD
    id1[/This is the text in the box/]


flowchart TD
    id1[/This is the text in the box/]

Parallelogram alt

flowchart TD
    id1[\This is the text in the box\]


flowchart TD
    id1[This is the text in the box]

Double circle

flowchart TD
    id1(((This is the text in the circle)))


flowchart TD
    id1(((This is the text in the circle)))

Links between nodes

Nodes can be connected with links/edges. It is possible to have different types of links or attach a text string to a link.

A link with arrow head

flowchart LR
    A-->B


flowchart LR
    A-->B

An open link

flowchart LR
    A --- B


flowchart LR
    A --- B

Text on links

flowchart LR
    A-- This is the text! ---B


flowchart LR
    A-- This is the text! ---B

A link with arrow head and text

flowchart LR
    A-->|text|B


flowchart LR
    A-->|text|B

Dotted link

flowchart LR
   A-.->B;


flowchart LR
   A-.->B;

Dotted link with text

flowchart LR
   A-. text .-> B


flowchart LR
   A-. text .-> B

Thick link

flowchart LR
   A ==> B


flowchart LR
   A ==> B

Thick link with text

flowchart LR
   A == text ==> B


flowchart LR
   A == text ==> B

An invisible link

This can be a useful tool in some instances where you want to alter the default positioning of a node.

flowchart LR
    A ~~~ B


flowchart LR
    A ~~~ B

Chaining of links

It is possible declare many links in the same line as per below:

flowchart LR
   A -- text --> B -- text2 --> C


flowchart LR
   A -- text --> B -- text2 --> C

It is also possible to declare multiple nodes links in the same line as per below:

flowchart LR
   a --> b & c--> d


flowchart LR
   a --> b & c--> d

You can then describe dependencies in a very expressive way. Like the one-liner below:

flowchart TB
    A & B--> C & D


flowchart TB
    A & B--> C & D

If you describe the same diagram using the basic syntax, it will take four lines. A word of warning, one could go overboard with this making the flowchart harder to read in markdown form. The Swedish word lagom comes to mind. It means, not too much and not too little. This goes for expressive syntaxes as well.

flowchart TB
    A --> C
    A --> D
    B --> C
    B --> D

New arrow types

There are new types of arrows supported:

circle edge
cross edge

Circle edge example

flowchart LR
    A --o B


flowchart LR
    A --o B

Cross edge example

flowchart LR
    A --x B


flowchart LR
    A --x B

Multi directional arrows

There is the possibility to use multidirectional arrows.

flowchart LR
    A o--o B
    B <--> C
    C x--x D


flowchart LR
    A o--o B
    B <--> C
    C x--x D

Minimum length of a link

Each node in the flowchart is ultimately assigned to a rank in the rendered graph, i.e. to a vertical or horizontal level (depending on the flowchart orientation), based on the nodes to which it is linked. By default, links can span any number of ranks, but you can ask for any link to be longer than the others by adding extra dashes in the link definition.

In the following example, two extra dashes are added in the link from node B to node E, so that it spans two more ranks than regular links:

flowchart TD
    A[Start] --> B{Is it?}
    B -->|Yes| C[OK]
    C --> D[Rethink]
    D --> B
    B ---->|No| E[End]

Note Links may still be made longer than the requested number of ranks by the rendering engine to accommodate other requests.

When the link label is written in the middle of the link, the extra dashes must be added on the right side of the link. The following example is equivalent to the previous one:

flowchart TD
    A[Start] --> B{Is it?}
    B -- Yes --> C[OK]
    C --> D[Rethink]
    D --> B
    B -- No ----> E[End]


flowchart TD
    A[Start] --> B{Is it?}
    B -- Yes --> C[OK]
    C --> D[Rethink]
    D --> B
    B -- No ----> E[End]

For dotted or thick links, the characters to add are equals signs or dots, as summed up in the following table:

Length	1	2	3
Normal	`---`	`----`	`-----`
Normal with arrow	`-->`	`--->`	`---->`
Thick	`===`	`====`	`=====`
Thick with arrow	`==>`	`===>`	`====>`
Dotted	`-.-`	`-..-`	`-...-`
Dotted with arrow	`-.->`	`-..->`	`-...->`

Subgraphs

subgraph title
    graph definition
end

An example below:

flowchart TB
    c1-->a2
    subgraph one
    a1-->a2
    end
    subgraph two
    b1-->b2
    end
    subgraph three
    c1-->c2
    end


flowchart TB
    c1-->a2
    subgraph one
    a1-->a2
    end
    subgraph two
    b1-->b2
    end
    subgraph three
    c1-->c2
    end

You can also set an explicit id for the subgraph.

flowchart TB
    c1-->a2
    subgraph ide1 [one]
    a1-->a2
    end


flowchart TB
    c1-->a2
    subgraph ide1 [one]
    a1-->a2
    end

flowcharts

With the graphtype flowchart it is also possible to set edges to and from subgraphs as in the flowchart below.

flowchart TB
    c1-->a2
    subgraph one
    a1-->a2
    end
    subgraph two
    b1-->b2
    end
    subgraph three
    c1-->c2
    end
    one --> two
    three --> two
    two --> c2


flowchart TB
    c1-->a2
    subgraph one
    a1-->a2
    end
    subgraph two
    b1-->b2
    end
    subgraph three
    c1-->c2
    end
    one --> two
    three --> two
    two --> c2

Direction in subgraphs

With the graphtype flowcharts you can use the direction statement to set the direction which the subgraph will render like in this example.

flowchart LR
  subgraph TOP
    direction TB
    subgraph B1
        direction RL
        i1 -->f1
    end
    subgraph B2
        direction BT
        i2 -->f2
    end
  end
  A --> TOP --> B
  B1 --> B2


flowchart LR
  subgraph TOP
    direction TB
    subgraph B1
        direction RL
        i1 -->f1
    end
    subgraph B2
        direction BT
        i2 -->f2
    end
  end
  A --> TOP --> B
  B1 --> B2

Limitation

If any of a subgraph's nodes are linked to the outside, subgraph direction will be ignored. Instead the subgraph will inherit the direction of the parent graph:

flowchart LR
    subgraph subgraph1
        direction TB
        top1[top] --> bottom1[bottom]
    end
    subgraph subgraph2
        direction TB
        top2[top] --> bottom2[bottom]
    end
    %% ^ These subgraphs are identical, except for the links to them:
 
    %% Link *to* subgraph1: subgraph1 direction is maintained
    outside --> subgraph1
    %% Link *within* subgraph2:
    %% subgraph2 inherits the direction of the top-level graph (LR)
    outside ---> top2


flowchart LR
    subgraph subgraph1
        direction TB
        top1[top] --> bottom1[bottom]
    end
    subgraph subgraph2
        direction TB
        top2[top] --> bottom2[bottom]
    end
    %% ^ These subgraphs are identical, except for the links to them:

    %% Link *to* subgraph1: subgraph1 direction is maintained
    outside --> subgraph1
    %% Link *within* subgraph2:
    %% subgraph2 inherits the direction of the top-level graph (LR)
    outside ---> top2

Comments

Comments can be entered within a flow diagram, which will be ignored by the parser. Comments need to be on their own line, and must be prefaced with %% (double percent signs). Any text after the start of the comment to the next newline will be treated as a comment, including any flow syntax

flowchart LR
%% this is a comment A -- text --> B{node}
   A -- text --> B -- text2 --> C


flowchart LR
%% this is a comment A -- text --> B{node}
   A -- text --> B -- text2 --> C

Styling and classes

Styling a node

It is possible to apply specific styles such as a thicker border or a different background color to a node.

flowchart LR
    id1(Start)-->id2(Stop)
    style id1 fill:#f9f,stroke:#333,stroke-width:4px
    style id2 fill:#bbf,stroke:#f66,stroke-width:2px,color:#fff,stroke-dasharray: 5 5


flowchart LR
    id1(Start)-->id2(Stop)
    style id1 fill:#f9f,stroke:#333,stroke-width:4px
    style id2 fill:#bbf,stroke:#f66,stroke-width:2px,color:#fff,stroke-dasharray: 5 5

Classes

More convenient than defining the style every time is to define a class of styles and attach this class to the nodes that should have a different look.

A class definition looks like the example below:

    classDef className fill:#f9f,stroke:#333,stroke-width:4px;

Also, it is possible to define style to multiple classes in one statement:

    classDef firstClassName,secondClassName font-size:12pt;

Attachment of a class to a node is done as per below:

    class nodeId1 className;

It is also possible to attach a class to a list of nodes in one statement:

    class nodeId1,nodeId2 className;

A shorter form of adding a class is to attach the classname to the node using the :::operator as per below:

flowchart LR
    A:::someclass --> B
    classDef someclass fill:#f96


flowchart LR
    A:::someclass --> B
    classDef someclass fill:#f96

This form can be used when declaring multiple links between nodes:

flowchart LR
    A:::foo & B:::bar --> C:::foobar
    classDef foo stroke:#f00
    classDef bar stroke:#0f0
    classDef foobar stroke:#00f


flowchart LR
    A:::foo & B:::bar --> C:::foobar
    classDef foo stroke:#f00
    classDef bar stroke:#0f0
    classDef foobar stroke:#00f

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