MD021 - No multiple spaces in closed heading
November 28, 2025 · View on GitHub
Aliases: no-multiple-space-closed-atx
What this rule does
Ensures there's only one space after the opening # and before the closing # in headings that use # symbols at both ends.
Why this matters
- Consistency: Extra spaces create uneven visual spacing
- Cleanliness: Single spacing looks professional
- Standards: Follows Markdown best practices for heading formatting
Examples
✅ Correct
# Heading 1 #
## Heading 2 ##
### Heading 3 ###
#### Heading 4 ####
##### Heading 5 #####
###### Heading 6 ######
❌ Incorrect
# Heading 1 #
## Heading 2 ##
### Heading 3 ###
#### Heading 4 #### (extra spaces at start)
##### Heading 5 ##### (extra spaces at end)
🔧 Fixed
# Heading 1 #
## Heading 2 ##
### Heading 3 ###
#### Heading 4 ####
##### Heading 5 #####
Configuration
This rule has no configuration options.
Automatic fixes
This rule automatically removes extra spaces:
- Leaves only one space after the opening # symbols
- Leaves only one space before the closing # symbols
Learn more
- CommonMark specification for headings - Technical details about heading syntax
- Closed headings - Alternative heading syntax