Wrong final radius drawing a circle

[RonaldoKnychala]

Hi, I'm having problems when drawing a circle entering the radius. I start creating circle, enter a radius (eg. 1200feet) and after it's done the circle ends up with less than what've I entered (eg.1020 feet), can anyone tell what I'm doing wrong ? TKS!

[DanPatterson_Retired]

are your visuals a different example since the numbers don't match... but I do see some inner and outer radius thing going on

[RonaldoKnychala]

Yes the visual are different too, what do you mean by inner and outer radius?

Sent from my iPhone

[DanPatterson_Retired]

I just tried with drawing a simple radius for a circle and I get the expected perimeter and area for a circle with a radius of 1000m

[RonaldoKnychala]

Hi Dan, yes yours look just right, mine when I do that the result is different.. IDK what to do

[DanPatterson_Retired]

It appears measurement issues are related to a coordinate system having 'tainted' the map.  Anything that may be added first to a map (or dataframe) sets the coordinate system.  I always suspect Web Mercator as the root problem when the measurement differences aren't purely a meters vs feet issue.

[RonaldoKnychala]

Tks for your insights Dan, yes I'm using Web Mercartor WGS 1984, and working with feet on my measurements, you thinks that's the problem? Should I change my spatial reference?

[DanPatterson_Retired]

That IS the problem.  Web Mercator produces erroneous measurements for length, perimeter and area.  It is well documented, but continue to use it for some reason

FAQ: Why are my map, distance and area measurements wrong when using WGS 1984 Web Mercator? 

And it isn't just esri, but anything 'Googly' that does mapping.  It is designed for looking at.,. not doing with.  Until they have automatic 'fixes' in all software, we have banned anything 'webbie' as basemaps or layers in our teaching, because the temptation to 'measure' something in some software that use it is too great

[RonaldoKnychala]

Tks Dan, I'm from Brazil and there I was using SIRGAS 2000, recently I moved to  Texas USA and thought that WGS 84 would be suitable, didn't know about that issue. Tks for letting me know!!

[JoshuaBixby]

Not to nitpick, but the issue isn't with WGS84.  There is nothing wrong, inaccurate, or imprecise about the WGS84 datum, it is the Web Mercator projection based on WGS84 datum that creates these issues.