The border-inline-end-width property sets how thick the border is on the inline-end side only.
01
Inline-End
Trailing side width.
02
thin
About 1px.
03
medium
Default ~3px.
04
thick
About 5px.
05
Length
px, em, rem.
06
RTL Ready
Direction-aware.
Fundamentals
Definition and Usage
The border-inline-end-width CSS property controls the thickness of the border on the inline-end side of an element. It is a longhand of border-inline-end and accepts the same width values as standard border width properties.
Unlike border-right-width, which always targets the physical right side, border-inline-end-width adapts to writing mode and text direction — useful for RTL layouts and multilingual interfaces.
💡
Beginner Tip
border-inline-end-width only sets thickness. Pair it with border-inline-end-style and border-inline-end-color, or use the border-inline-end shorthand.
Foundation
📝 Syntax
border-inline-end-width accepts keyword or length values:
Accepts thin, medium, thick, or any length such as 2px or 0.25em.
Only affects the inline-end border side; other sides keep their own widths.
A visible border-inline-end-style is required for the width to show.
The physical side mapped to inline-end depends on direction and writing-mode.
Default is medium, typically about 3px in most browsers.
Cheat Sheet
⚡ Quick Reference
Question
Answer
Initial value
medium
Applies to
Inline-end border thickness
Inherited
No
Animatable
Yes (as length)
Common use
Thick trailing dividers, accent end borders, RTL-safe layouts
Defaults
Default Value
The default value of border-inline-end-width is medium, which browsers typically render as about 3px when a visible border style is applied.
Reference
💎 Property Values
Value
Example
Meaning
thin
border-inline-end-width: thin;
Thin border, typically about 1px
medium
border-inline-end-width: medium;
Default thickness, typically about 3px
thick
border-inline-end-width: thick;
Thick border, typically about 5px
Length
border-inline-end-width: 2px;
Exact size in px, em, rem, etc.
initial
border-inline-end-width: initial;
Resets to the default medium value
inherit
border-inline-end-width: inherit;
Inherits from the parent element
Keyword Width Comparison
thin~1px
medium~3px default
thick~5px
Scope
Inline-End Width and Writing Modes
border-inline-end-width always applies to the end of the inline axis. The physical side changes with text direction.
LTR (direction: ltr)
5px inline-end (usually right)
RTL (direction: rtl)
5px inline-end (usually left)
Compare
border-inline-end-width vs related properties
Property
Targets
Best for
border-inline-end-width
Thickness on inline-end only
Thick trailing dividers in logical layouts
border-inline-end
Width, style, and color on inline-end
Setting the full inline-end border in one rule
border-inline-end-style
Line style on inline-end
solid, dashed, or dotted patterns
border-right-width
Physical right side thickness
Fixed LTR-only layouts
Preview
👀 Live Preview
A box with a 4px blue inline-end border:
4px border on the inline-end side.
Uses border-inline-end: 4px solid #2563eb;.
Hands-On
Examples Gallery
Try border-inline-end-width with pixel values, keywords, relative units, and RTL layouts.
📚 Basic End Border Widths
Control thickness on the trailing inline border side.
Example 1 — 5px Inline-End Border
Set a 5px width on inline-end with style and color longhands, matching the reference tutorial.
border-inline-end-width-5px.html
<style>p{border-inline-end-width:5px;border-inline-end-style:solid;border-inline-end-color:black;padding:0.75rem 1rem;}</style><p>This paragraph has a border width of 5px on the inline-end side.</p>
This paragraph has a border width of 5px on the inline-end side.
How It Works
Three longhands work together: width sets thickness, style makes the line visible, and color sets the line color. In LTR, inline-end is often the right edge.
Example 2 — thin, medium, and thick Keywords
Use keyword widths for quick, browser-defined thickness on the inline-end side.
thin, medium, and thick are keyword widths. Browsers map them to approximate pixel sizes — useful when you want consistent relative thickness without exact px values.
🎨 Relative Units and RTL
Scale end borders with text size and direction.
Example 3 — em-Based Inline-End Width
Use em so the end border scales with the element’s font size.
The 6px width still applies to inline-end. In RTL, that is usually the left side — no separate border-left-width rule is needed.
🧠 How border-inline-end-width Works
1
Width reserves space
border-inline-end-width sets how much room the border takes on the trailing side.
Width
2
Style makes it visible
A visible style such as solid or dashed is required to see the width.
Style
3
Direction maps the side
Inline-end maps to the correct physical side for LTR or RTL.
Mapping
=
▪️
Sized end border
Only the trailing inline edge shows your chosen border thickness.
Compatibility
Modern Browser Support
The border-inline-end-width property is supported in all modern browsers, including Chrome, Firefox, Safari, Edge, and Opera.
✓ Baseline · Modern browsers
Logical inline-end widths in today’s browsers
Chrome, Edge, Firefox, Safari, and Opera support border-inline-end-width in LTR and RTL layouts.
94%Modern browser support
Google Chrome87+ · Desktop & Mobile
Full support
Mozilla Firefox66+ · Desktop & Mobile
Full support
Apple Safari14.1+ · macOS & iOS
Full support
Microsoft Edge87+ · All versions
Full support
Opera73+ · Modern versions
Full support
border-inline-end-width property94% supported
Bottom line: Use border-inline-end-width for direction-aware trailing border thickness in modern multilingual projects.
Wrap Up
Conclusion
The border-inline-end-width property controls how thick the trailing inline border is. Use it for accent dividers, thick end highlights, and layouts that stay correct in LTR and RTL writing modes.
Combine it with style and color longhands, or use the border-inline-end shorthand when you want all three values together.
Set border-inline-end-style alongside width for visible borders
Use em or rem when the border should scale with text
Prefer logical end widths over border-right-width in RTL layouts
Test end border widths in both LTR and RTL
Use the shorthand when width, style, and color are all needed
❌ Don’t
Set width alone without a visible border style
Assume inline-end is always the physical right side
Mix conflicting physical and logical width rules on the same element
Rely on keyword widths when you need pixel-perfect design
Hard-code RTL overrides when one logical rule suffices
Summary
Key Takeaways
Knowledge Unlocked
Five things to remember about border-inline-end-width
Use these points when sizing trailing inline borders.
5
Core concepts
▪️01
End width only
Trailing side.
Purpose
⚡02
Default medium
~3px.
Default
🔀03
thin / thick
Keywords.
Values
🌐04
RTL ready
Direction-aware.
Logical
🛠05
Needs style
Width longhand.
Usage
❓ Frequently Asked Questions
The border-inline-end-width property sets how thick the border is on the inline-end side only — the trailing edge along the text flow direction.
The initial value is medium, which browsers typically render as about 3px when a visible border style is set.
In horizontal left-to-right text, inline-end is usually the right side. In RTL, inline-end is usually the left side.
Width alone does not draw a border. You also need a visible border-inline-end-style such as solid or dashed, and usually a color.
border-right-width always targets the physical right side. border-inline-end-width follows writing direction, so the same rule works in LTR and RTL layouts.