How to show the 2D dimensions

Operating system: Windows 10
Slicer version: 4.7.0-2017-09-21

I wanted to measure the 2D dimensions in Azial and Sagittal plane. I found that the scale is different. Is there a reason for that?
The width of sagittal slice appears longer although the frame is smaller than the axial one.
I attached the pic that shows that the scale is different (from the ruler bar).
Thank you!
sagittal and axial

The scales on the image look all correct. You may want to click on the “Reset field of view” button or zoom out the slice view to see the complete image.

I understand and i pressed the reset button on each slice. It seemed that it is something related to the data itself.
Thank you