If you have pad patterns that come as an image file (like the ones I have here on this site). You can use “Word” or other word processing programs to adjust the pattern length and width. Just insert the image into a word document file (or similar). Then click the image once, and you should have little squares at the corners.
This makes the image “dragable” – so you can put your mouse pointer on the box in the corner, and “drag” the image to make it larger or smaller (larger in this example).
Once you have dragged it to the size you think is right, you can print it out and measure it with a ruler and see if it’s printed to a size you like. If not, you can try again. Using this method, you should be able to modify the pattern by making it longer, wider, narrower, shorter… just by dragging the image as required.