I looked all over online and this is the main way to hem pants using the original cuff. First, try on your pants and see what length it needs to be altered. Make sure both sides are the same and pin them in place.
The place where you sew is right under the original stiching as close as you can. Use a dark navy thread so it won't be seen.
Can you tell the difference? The left one is the finished one and the rest of the material is tucked into the pants and ironed. The bottom cuffs look the same!
Here is the inside of a completed pant leg with the extra fabric inside. Some blogs said that you can stitch up that extra fabric by hand stitching on the sides but since I had so much fabric I ended up cutting the extra fabric but careful it frays after washing so you might need to use another stitch or surge it.
Ta Da!!!! Pants that fit