As a former CAD draftsman I always found the snap function in Illustrator very inaccurate.

But now in AI CC I find it even more inaccurate. Am I the only one? Is there something one can do in order to make Illustrator snap more accurate?

100% Zoom:

The green Line would indicate that the mouse has the line in range but the purple line is not aligned. That doesn't make sense.

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1600% Zoom Still the same but a bit closer

The colored lines would indicate that the alignment would fit the two lines together but it doesnt.

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6400% Zoom At this zoom ratio its possible to align the lines 100% what a miracle.

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So why does AI indicate the the lines are aligned, when they clearly aren't? Thanks for any help. (By the way: The useless "Align new elements to the pixelgrid" is disabled).

  • 6
    Bug with smart guides that's been present since roughly CS4. Complain to Adobe, Lord knows I have.
    – Scott
    Commented Sep 16, 2014 at 6:29
  • I can relate to your troubles, but maybe you're expecting the wrong things from the wrong software. While I think it should be able to perfectly align everything nice and vectory, we have to keep in mind what the main purpose for Illustrator is; illustratin', making artwork. It's not a CAD program, nor should we expect it to be.
    – Tom
    Commented Sep 16, 2014 at 8:02
  • 1
    @Tom I don't think it's unreasonable for an application which touts alignment functions to actually align things. In addition, Illustration is not always freeform in nature. I don't create CAD artwork, but I still like things to align when I ask them to.
    – Scott
    Commented Sep 16, 2014 at 8:47
  • Fair enough, but when something's just that annoyingly teeny tiny bit unaligned at 3200%, chances that people are gonna notice are very slim. This, however, should not be an excuse for Adobe to address the issue.
    – Tom
    Commented Sep 16, 2014 at 8:57
  • So thats a bug?! :( I guess it's not unreasonable when I expect smart-guides to guide smart. Of course it's not a CAD but please… How hard can it be?
    – KSPR
    Commented Sep 16, 2014 at 9:17

1 Answer 1


Illustrator perform methods for drawing on screen differently than CAD. Illustrator draw everything mathematically. CAD are using calculations to show accurate, but not mathematically precise on screen. In your example: you just need to understand that it's not possible to draw half pixel on screen (even on retina displays) and mach it with other half pixel and match it on different zoom levels (meaning different proportion half pixels) without adjustments and loosing precision.

If you need absolute precision for your objects, use object options. For example, you need to place guide at 10 cm from left side of the artboard. Draw guide anywhere on artboart, select guide (make shure View -> Guides -> Lock Guides is unchecked) and put value 10 cm in X coordinate. How to change position of guide in Illustrator Now make another guide and place it at, in example, 30 cm from left corner. Draw 3 rectangles exactly 20 cm wide and align it to the guides. Result will depend on what you will choose in Align stroke options. Illustrator object align stroke options Now let's try other example. 20 and 120 ellipses with thin line. Notice a moire drawn buy Illustrator in some parts of overlapping. More textures in Illustrator If you will print this object, it will be accurate and the only moire could be printed will be depending on liniature of printer. But you can't make so perfect drawing on screen just because screen is not so perfect to draw such a precise lines.

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