# What is going on with scale on Inkscape?

I am using Inkscape 0.92 and I am trying to make a 1:1 size image of a physical part. The measurements of the part are 9.875 inches wide, by 6.875 inches high. However, when I zoom to a 1:1 and hole the part up to it, the rectangle on screen is much bigger. So I did some googling and found edit/preferences/interface zoom correction factor. I thought, this would fix the problem. I whipped out some callipers, set it to exactly one inch, and then scaled the on-screen ruler's inch to match my calliper's inch. I then created a 1 inch rectangle and measured it with my callipers and it was a perfect 1 inch square. Then I created the full size rectangle and it is not the right size. It is longer and wider than it should be.

Anyone know whats going on here?

Below are screenshots of the issue. The blue square is set to 1 inch square. Holding a ruler up to it shows it to be exactly 1 inch square. However, putting the ruler to the red square, which is manually set to 9.875x6.875 inches, you can see its 10.5 inches on the ruler. If the one inch square is 1:1, why isnt the bigger rectangle?

• See my answer - you need to measure to something larger. Using 1 inch is too small and will increase the size error. May 11, 2017 at 20:26

Your measurement is probably off, also in the image your ruler is not entirely straight. You should always erasure correction measurement is done on a BIG dimension to account for rounding and measurement error. Better yet use manufacturer information of this.

10.5/9.875 is about 6 % off

This is well withing error of measurement on small scale. Had you measured the screen by full width then youd be much ore closer to the truth as your measurement errors would fold out.

• The ruler is just for show. As I said in my post I used calipers to measure and set the scale. The 1 inch cube is exactly 1 inch. May 11, 2017 at 15:03
• @Keltari i doubt you can measure that exacly since there is no reference datum to measure against. May 11, 2017 at 15:22
• But there is. Built into Inkscape May 11, 2017 at 15:23
• @Keltari i mean for your caliper. There is also no exact measurement. May 11, 2017 at 15:24

In Preferences, select Interface.

Resize the dialog box so you can see the largest measurement possible. In my example I used 11 inches as the measurement, and set the zoom correction factor so it matches that measurement measured against a ruler.

Then in the Inkscape menu hit `View` > `Zoom` > `Zoom 1:1`

The onscreen image should then show the image at actual size. I tried this and it worked for me, and it's pretty damned close to the actual size. 100% accuracy is probably not possible.

A small amount of error shouldn't matter much, because when printed with no scaling, the images should print to exact scale.

• This is exactly the same answer as i said. 100% accuracy os not possible since a discrete system will always have the possibility to be off by 1-2 pixels. Again bigger measurements accumulate less errors. May 12, 2017 at 3:30
• I would like to add that a discrete system has a inherent 1- 2 pixel error. So if you measure the factor on one inch you incur a 1-2% error while on a 10 inch measure you get a 0.1-0.2% error from that source. Offcourse you will have other errors in measures. So you would be better off checking the value from the panels specification sheet. May 12, 2017 at 3:40