How to Change Stroke Thickness in Inkscape

Adjusting the thickness, or width, of a stroke in Inkscape is a fundamental skill for creating clean vector graphics. This guide provides a quick, step-by-step walkthrough on how to locate and use the Fill and Stroke dialog, modify outline weights using precise numerical values or presets, and troubleshoot common scaling issues when resizing objects.

Step-by-Step Guide to Adjusting Stroke Width

To change the thickness of a line or shape outline in Inkscape, follow these steps:

Select the Object: Click on the Select and Transform Objects tool (the black arrow) from the left toolbar, or press S, and click on the object you want to modify.
Open the Fill and Stroke Menu: Go to the top menu bar, select Object, and then click on Fill and Stroke… (Shortcut: Ctrl + Shift + F on Windows/Linux or Cmd + Shift + F on Mac). This will open a settings panel on the right side of your workspace.
Navigate to the Stroke Style Tab: In the Fill and Stroke panel, look for the three tabs at the top and click on Stroke style.
Modify the Width: Inside the Stroke style tab, you will see a Width field. You can:

Type a specific numerical value directly into the box.
Use the up and down arrows next to the box to change the thickness incrementally.
Change the measurement unit (e.g., px, mm, in, pt) using the dropdown menu next to the width value.

Additional Stroke Customizations

While in the Stroke style tab, you can further customize the appearance of your stroke to match your design needs:

Join and Cap: Change how the corners of your paths meet (Miter, Round, or Bevel join) and how the ends of open lines look (Butt, Round, or Square cap).
Dashes: Click the Dash dropdown menu to convert a solid line into various dashed or dotted patterns.
Markers: Add arrowheads, dots, or custom shapes to the start, middle, or end of your paths.

Troubleshooting: Stroke Changing Size When Resizing Objects

A common frustration in Inkscape is when a stroke becomes thicker or thinner when you scale an object. To toggle this behavior on or off, look at the Tool Controls Bar at the top of the screen while the Select tool (S) is active.

Look for the four icon toggles on the far right. The first icon resembles a corner with a stroke: “Scale stroke width by the same proportion”.

To keep stroke thickness constant regardless of object size, make sure this button is unpressed (disabled).
To scale stroke thickness proportionally with the object, make sure this button is pressed (enabled).