Picture-heavy post! But, hey. Its a tutorial and I like when there are pictures. These are the jeans I bought from Goodwill for $1.50. I decided I didn't like the flare because I usually wear boots and I like to keep my hems dry in the winter. They happen to be the current style as well... In the picture I've already skinnified one leg, but I'll walk through the steps to get there.
There are a couple different options you could use to adjust the voluminous width of the pant legs, but the simplest is to try on the pants inside out, then put a safety pin where you want to start bringing the leg in (probably around the knee), another mid-calf, and one at the ankle. To save your eyes from yet another awkward self-portrait of my legs, I didn't take that picture. However, after I replaced and augmented the line of safety pins with regular pins, I checked the taper against a pair that fit to make sure I was doing things right. This is also another way you could go about getting measurements, but you can't go wrong with the pin method...it's tailored to your body.
As you can see, my bottom pin shows 3 inches being removed.
You can record the "trimmage width" and "trimmage height" to use for the other leg.
Look at that pretty line of pins....
Sew along your line of pins, making sure to backstitch at the beginning and end to lock your stitches in.
If you run into the seam during your sewing jaunt, just make sure it lies flat as it goes under the presser foot. We don't like bulges.
As you can see, my seam didn't line up perfectly with the manufactured one. If you are a perfectionist, you could try. I'm more of an instant gratification type of girl. This is where you try your jeans on to make sure they fit, and that they look good.
Once you check for proper fit, do the same thing for the second leg. Once both legs have been sewn and you are happy with how your legs are hugged in denim, keep your seam from fraying by running a serger alongside, or by using a zig zag stitch. I used the max number of stitches per inch that my machine would allow. I like to clip the excess after I zig and zag because then I don't have to worry about distracted driving. If you are really savvy with reuse and don't mind a slightly padded leg, you could forget about the zig and zag and clip, and just leave the extra fabric. That way, when you'd rather die than be seen in skinny jeans, you can simply remove the seam and suddenly you have new pants. Everyone loves a 2-fer, right?
et voila!
My photography skills are amazing, no? I think I just need a tripod.