Sorry, Misty, M'dear. You're going to have to do some math if you want to add length proportional to the added width.
Let's say you increase width from 1.5" to 2". the extra half inch is 1/3 the original size. so your new length should be 1-1/3 times the old length.
since i've never seen a ruler that divides inches into thirds, you'll have to round up or down.
of course, without seeing the pattern i can't even guess whether the rounded sizes will work. try these with scraps of paper to test.