I am fairly new to the wonderful world of icon design and I have a recurring issue that I find difficult to deal with. for me, consistency in line thickness, shape sizes and colors is very important to create a well designed piece.

However I seem to run into an 'optical illusion' problem often. The latest icon I am creating for example should represent an old bike. I have set my line stroke to 10px and have drawn a small circle of 10x10px. Yet all three of my shapes seem to be of different size and line thickness to the eye.

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However as you can see by the orange balls I included, the lines really are all the same size.

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How do I prevent such things from happening? It looks very awkward to me. I could reduce and increase the size here and there so it pleases the eye, but then it is not technically correct anymore...

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    FYI these bikes are called "penny-farthing" bikes and the big wheel is often thicker than the smaller wheel, so that could be part of the reason why it looks off to us. Commented Jul 3, 2017 at 14:22

1 Answer 1


You have two choices: either change the line thickness so that it looks right, or leave it alone. There are no other ways.

Example image

Nobody except you will probably realise that it's not "technically correct", unless they have OCD and use a ruler to check, or magical eyes that don't suffer from the same optical illusions that plague the rest of the human race.

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    I think one takeaway here is that "technically correct" doesn't actually matter. (Well, I can think of extreme edge cases of logo design... for engineers or something!) but in fact design is art. Art is design. And art is to please the eye of the beholder... or in our case... the client. Commented Jul 4, 2017 at 15:26

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