Scaling an SVG without scaling the stroke

Three icons: one small, one enlarged, with stroke enlarged to match, and one enlarged with the stroke the same width as the original small version.

A few days ago, I ran into a little problem when using SVGs. I’d created a reusable set of SVG symbols for a project I was working on, and started sprucing it up with all the pretty icons my designer gave to me. As we all know, one of the biggest benefits to using SVG is the “scalable” part of it, meaning that graphics render perfectly at and size, no matter the original size of the graphic. I’m a huge fan in general of SVG, and implementing them into this project was a no brainer for me.

However, a few of the icons in the design consisted of strokes, and those strokes were always 1px in width, no matter the size. When you scale an SVG, it scales everything about it, so an icon that’s scaled up two times would have stroke widths that are double the size of the original. One such example was a “+” icon that indicated there was more content. I had to reuse that icon at small and large sizes, but:

  1. I wanted the stroke width at all sizes to be 2px
  2. I wanted to create one graphic that I could reuse at any size without scaling the stroke width

Enter The Vector Effect Attribute

One of my favourite things about programming is being faced with a problem. It challenges you to research and find solutions. In this case, I stumbled upon the vector-effect attribute, which conveniently has an available value called non-scaling-stroke. It does exactly what it says, i.e. prevents strokes from scaling as an SVG scales.

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I’d see a scaled up icon including scaled up effects. This one’s dimensions are 4 times the size of the original view box. As such, the stroke would render at 8px. In order to circumvent this, I added the vector-effect attribute to the paths on the original graphic, and set the value to non-scaling-stroke, like this:

Code language: HTML

<circle vector-effect="non-scaling-stroke"/>
<path vector-effect="non-scaling-stroke"/>
<path vector-effect="non-scaling-stroke"/>
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