Consider the image below, where the selected vertices form an incomplete circle (that was derived from a circle), which measures 12.5mm. I would like to change the radius of the circle formed by the vertices to instead measure 12.8mm.

With the vertices selected, and with 3D cursor set as the transform pivot point, I can press S (scale) then Shift+Z to scale the circle, and it scales as I want it to, but it will only scale based on a percentage, rather than an absolute measurement.

I would like to type .3 to have the radius grow by .3mm.

I know how to do it the long and tedious way by adding a new circle the size I want, then reworking all of the geometry, but I really want a fast and simple way to scale up a circle-like shape's diameter by absolute dimensions.

EDIT: It's possible to use a percentage difference calculation, which in this case is a difference of 2.4%, which would be a scale operation with a value of 1.024. But it would be nice to use dimensions instead of reverse-engineering a percentage.

Blender Scale

  • $\begingroup$ This is a feature request, and as such should be posted on rightclickselect.com $\endgroup$
    – TheLabCat
    Dec 14, 2021 at 3:15
  • 2
    $\begingroup$ Not exactly a feature request IMO, he just wondered if there was a way to do it. $\endgroup$ Dec 14, 2021 at 3:17
  • $\begingroup$ Correct. The question was how to do it, based on the assumption that there was already some option, plugin, or other method to already do this. $\endgroup$
    – Nick
    Dec 14, 2021 at 4:45

1 Answer 1


You can use Vertex snapping.

  1. Set pivot point to the center of your circle (3D cursor in your case should work)
  2. Add a circle with the desired radius
  3. Set Vertex Snapping > Active and check Project onto self
  4. Select your shape with one vertex active and Scale. It will snap with the active vertex.

enter image description here

  • 1
    $\begingroup$ nice idea!! +1! $\endgroup$
    – Chris
    Dec 14, 2021 at 11:09
  • 1
    $\begingroup$ most of the times I can't be bothered and just eyeball it tho :)) $\endgroup$ Dec 14, 2021 at 12:08

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