Complementary colour different on illustrator than everywhere else

[magguunicorn]

Hi everyone!

I am trying to find the complementary colour of hex #3ABFCF
If I use Illustrator colour guide in RGB I get this: #DC6B33

But everywhere else, with online tool (canva colour wheel, color-hex.com, etc.) I get #CF4A3A

It is also supposed to be RGB.

The 2 colours are very different. And I don't know how to explain this to my client. 

I've checked everywhere on Google and I can't find an explanation.
Does anyone understands where this difference comes from?

Thank you in advance

[Mike_Gondek · Accepted solution]

There is no 100% exact formula for a complimentary color in Hex. To figure that a color model conversion is used to go between RGB and HEX. If you keep searching on web you will probably find a third color.  The issue I see is there is a color difference between those colors, so you will need to physically look at this and choose the better of the colors, or one in between.

If you want to put more time into this try doing teh complimentary colors in RGB, then visually that you have close color matches in Hex to see where the color may be falling off. 

[magguunicorn]

Hi!

Thank you!

I did find a third colour: #C54030
When you say to try to do the complementary color in RGB, do you mean to substract the values fron 255?
I am also trying to understand why there is such discrepancy in Illustrator between the colour guide and the colour panel complementary values.

[Ton Frederiks]

This is what you get if you select the complimentary colors in Illustrator's Recolor Artwork.

[Myra Ferguson]

If you go to Illustrator's Color panel (as opposed to the Color Guide panel) and select Complement from the panel menu, you do get #CF4A3A. On this page, you'll find a description of the process Illustrator uses to find the complement from the RGB value.

[magguunicorn]

Hi Myra!
Thank you so much for this, I had no idea I could find a complementary colour on the color panel. Do you know why it is so different on the color guide? Isn't it supposed to be the same?

[Myra Ferguson · Accepted solution]

Mike is right. There are different approaches to finding the complement of a color.

The approach used in the Color panel takes the sum of the highest and lowest RBG values and each value for RGB is subtracted from that number to find the complement which finds #CF4A3A.

It looks like the Color Guide uses the HSL approach

The approach used that found #C54030 as the complement takes a color and subtracts it from white to get its complement.

I couldn't find which approach the Color Guide uses, but it could be one based on HSL. 

The reason why they're different would have to do with the decision to use a particular approach when each feature was created.