How to make an object thinner or thicker WITHOUT changing the length or width of the object - on Illustrator?

I took a picture of a letter that was written on other software, and I'm trying to make it thicker or thinner while keeping the original size. What's the best way to do so?

N.b. this letter isn't taken from illustrator fonts, otherwise, I knew how to deal with it by stroke function. But this isn't the case here, of I'm trying to do just the same but with an object. enter image description here

  • 1
    This is illogical. Any change in "thickness" is going to change the width. -- In any event, merely reduce/increase the brush size.
    – Scott
    Dec 12, 2020 at 22:16
  • @Scott Why? if we change the size from the internal side, the letter would in the same length and size but with a different thickness. This is on what my logic based on. Dec 12, 2020 at 22:41
  • 1
    yeah.. I suppose. I think it would take very deliberate and manual editing in order to do that.
    – Scott
    Dec 12, 2020 at 23:06
  • 1
    Hi. Welcome to GDSE. Do you want to increase the size of the stroke but still have the letter fit within the same bounding box? If so, I think you'd have to manually edit it. There's nothing automatic in Illustrator that will do this. Also the edits required would be different for each letter.
    – Billy Kerr
    Dec 12, 2020 at 23:47

1 Answer 1


enter image description here

I guess your letter is a closed shape like the K in image 1.

You can make a new version by applying Object > Path > Offset path with negative offset (ungroup and delete the extras) Unfortunately it's lower and narrower than the original. The grey shape below is a rectangle with the same dimensions as the bounding box of shape 1.

But nothing prevents you stretching the new version (=2) wider and higher. It's stretched to original width and height (=original bounding box dimensions) in image 3. Unfortunately I haven't found a way to make the stretching 100% automatically. Maybe a competent programmer can do it.

As well you can make a new version with positive offset and shrink it to the original width and height.

ADD: to apply the offset path to a traced bitmap image the tracing must be expanded. This generates the editable final tracing result. Before applying Object > Live trace > Expand you can still change the tracing parameters and the result isn't editable.

To get a solid black shape without a white background use tracing mode Black&White with option Ignore White=ON. It doesn't harm if the black shape is actually several separate parts.

  • Changes width and height though.
    – Scott
    Dec 12, 2020 at 23:31
  • Maybe the questioner judges soon is it remarkable.
    – user82991
    Dec 12, 2020 at 23:59
  • Thank you for the answer, but in fact, the function Path > Offset isn't available (it appears as grey) for the image. I have no idea why. So I couldn't judge this method. Does it work for you if you copy an image and then click on object > image trace > make? Dec 13, 2020 at 1:05
  • @UbiquitousStudent your screenshot appears to be a simple 15pt rounded brush stroke.. you can merely resize the brush stroke.
    – Scott
    Dec 13, 2020 at 3:21
  • Oh, I didn't notice I uploaded the wrong image, the specific illustration on the screenshot doesn't represent my question well. I'll update it. Dec 13, 2020 at 3:25

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