Newbie. Simple Box

[Jonyskids]

I am trying to make a template. 

I need a canvas of 2.6875" x 3.21875", I nailed it no problem

But then I need a box the creates a border that is 39" thick or 2.2975" x 2.82875"

I can not seem to define this box by these measurements.

Any help is appreciated and apologize for the simple question.

[Blighty]

The first thing to understand is that Gimp (and all bitmap editors) work in pixels, not inches. Only whole pixels, there cannot be fractions of a pixel. If you specify a size in inches the resolution you specified (dpi) is used to calculate the size in pixels. This is rounded to nearest whole pixel size. This creates a small variation in the inch size that you initially specified.

Quote:a border that is 39" thick or 2.2975" x 2.82875"

I don't understand this part.

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OK, I think this is what you mean:
2.6875 - (2 x 0.39) = 1.9075
3.21875 - (2 x 0.39) = 2.43875

I created a new image size 2.6875" x 3.21875", 300dpi.

I then created a rectangular selection as per the image below.
Click inside the selection to finalize.
Bucket fill with colour you require.

Note: you will still get small variations in inch sizes when rounding to the nearest whole pixel takes place.

[Jonyskids]

Thank you so much. You did indeed catch my mistake by adding the multiple of 2. I was also struggling because I had aspect ratio set to fixed.

Thank you.