There is another issue here as well. The math is based on waist to knee. If one lengthens that measurement (meaning you want it longer than waist to knee) then the widest part of the kilt is actually lower than it should be. so it won't fit around the hips properly and it will pull. The reverse will be true if one goes for a shorter kilt and it will be too big around the hips.
If we know what the actual length is going to be compared tom the true waist to knee measurement we can make the correct adjustments.