Feature request - For Circle Tool - Specifying Diameter

Hi folks.

The Circle tool allows only a radius as input. It would be very useful to also have the possibility of specifying a diameter instead.

This addition could be in the form of a prefix like d or D added in front of a numerical value with or without unit suffix.

For example, using inches while the model unit are set to millimeter would ask for D152". Of course, if the unit for the diameter are the same as for the model, no suffix is needed.

The d or D could be entered as a suffix but it may prove more difficult to parse two suffix in a row like 5 1/4"d or 167mmd.

Also, although I know that a diameter can be entered and then followed by /2 to tell SU to use it as a radius, it is not feasible with complex imperial units. With metric units, like millimeters, entering, for example, 150/2 in the Dimension Window, effectively results in a circle with a radius of 75 mm. Try it now with a radius of 7 3/8". Good luck. You will need to type 7 3/8/2. SU does not accept that and tells you “invalid length entered”. Using a prefix would simplify all that.

Just ideas.



I don’t used “D” as any of my shortcuts, but if anyone did, it would create some problem for people who does if it is suffix?

I want to expend on this, because i usually do /2 for typing diameter as you said (being in metric world helps :smiley: )
I thought it would be a good idea to do a bit more complex math with using = as prefix. and perhaps get sketchup ready for some math inputs such as =(7' 3/8")/2
I just tested this but typing 7 3/8/2 doesn’t work. (invalid length entered)
7' 3/8"/2 Doesn’t work either, but instead of throwing error, it will just draw 7’ 3/8"
All in all, 7 3/8/2 doesn’t really make sense anyways.

The limited ability to “do math” in the Measurements box is really just an accidental consequence of supporting fractions. As a result, the existing parser isn’t smart enough to understand expressions with more than one ‘/’, with parentheses, or with other arithmetic operators. The idea of prefixing a math expression with ‘=’ is similar to what spreadsheets do and to me seems like a good approach.


Thank you for your input @slbaumgartner.
I don’t want to be a copy-cat, but Revit takes = before taking arithmetic operations in value. - FYI

I agree Jean. I would very much like the ability to specify a circle with a diameter also.

I’ve used sketchup for a long time for machine drawings and general engineering. I often have to draw circles in sketchup from the diameter. I did a search today and noted that in Layout, I can simply type the diameter with a “d” after it and it will draw the circle of the apropriate diameter. This functionality doesn’t appear to be replicated in sketchup. I also noted that I can simply add “/2” for whole numbers, though this doesn’t seem to work when I type in a decimal diameter, outputting a circle of the radius entered, and seemingly ignoring the “/2”.

There seem to be a whole range of work arounds online, drawing circles and scaling to 0.5 etc. In the end, I draw mostly with Microsoft excel open, with a function page set up to do the calculation. This is a very inelegant solution, though the best I’ve been able to come up with . It requires me to type the number in, then transcribe the answer into sketchup, leaving it open to typos, etc.

Replicating the functionality of layout, where a “d” can be typed after the decimal diameter seems to be the most elegant solution to me and would make the existing functionality in Layout consistent across the SketchUp software.


I’ve found it to be good practice for dividing by 2 in my head.

You could use the calculator included with Windows.

I too wish that I could diameter or radius how can sketch up be taken serious when small things like this are not there?