Unless it's a UGC, I never use legal sized paper...
I made my own print templates for each style of case that I use.
Here is my method, hopefully it will help you.
Grab a ruler, measure out the diameter of the INSIDE SLEEVE in MILLIMETERS.
With the case closed, measure the front, back, and spine horizontally. Then just measure vertically. Write all these numbers down and label them accordingly. Add the front back and spine together and write it down and label it too. For a better fit, I would subtract a few millimeters from the 2 main measurements.
You now have 5 measurements.
Open whatever program you use to edit/print your covers and start a new project. Put in your your vertical and horizontal (the front back and spine measurements you added together), make sure it's in millimeters, and set the DPI to 600 (I prefer 600, but if you are using a bit slower of a computer I would recommend 300).
If you can, name your project and then click NEW or whatever.
Once it is created, set a guide at your back measurement, then add your back and spine measurements together and set your new guide at that.
Now save your project. That is now your custom template for whatever case you are using.
Now drag the cover you want to do into your project. Stretch it to fill your rectangle completely and if you did it correctly, it should fit pretty good or might possibly need some minor alterations.
Make sure BORDERLESS IS SET TO OFF. Click print!
BLAM!!
If you followed these directions, you should never EVER have a problem printing again.
If you do... Well I'm sorry to tell you, but you can't measure for shit...
