Here's my easy way to hem a pair of jeans. In my case, I bought a pair of maternity jeans from Goodwill for $10 (I know, it was like a high end Goodwill) that had already been hemmed by their first owner to hit my ankle bone. Not satisfied with the high water look, I hemmed them into capris.
-Sewing machine that can handle thick fabrics using a straight stitch
-Sharp pair of fabric scissors
-Thread to match your pair of jeans (I chose navy)
Try the jeans on and mark where you'd like them hemmed. Take them off and measure the total length of that extra amount of jean you want gone. Then half that measurement and fold the excess accordingly. In my case, I wanted a total of 7 inches hemmed. So I folded the jeans to measure 3.5 inches. Pin the fold in place.
Sew a straight stitch right next to the existing hem on the outside of your fold. The presser foot I have attached in the pic plops the needle down on the far left of the foot, a perfect guide. This can get tricky depending on the width of your jean leg opening. The smaller the opening, the harder it is to keep from sewing the leg closed.
Stop and have a snack. Especially if you're pregnant.
-I didn't know my camera could take such a good food picture-
And don't worry, I munched on this healthy mix for about 5 minutes and then switched to Rolo's and Life Savers.
Caution: Don't get too distracted by your snack, lest you sew without looking and sew your folds together as mentioned previously. The seam ripper is my most used sewing tool.
After carefully sewing your straight stitch, turn the excess jean material up inside your jeans. And you'll have this.
Looks nice on the outside, bothersome on the inside. Step 4 will fix it.
Sew a top stitch (perhaps the correct term) on the outside of your newly hemmed jeans right next to the original hem that you 'saved' by sewing in a flap.
You'll have this. Unless you're showing someone how you hemmed your own jeans, no one will notice if you use a coordinating thread.
To lose the bothersome-ness, carefully turn the flap back out and cut to the LEFT of your two modifying stitches.
I say carefully because if you're not, you'll accidently cut through the good side of your newly hemmed jeans. Rats. Luckily these jeans are distressed already so once through the wash should fray this and essentially hide it.
I hope it made sense and if it doesn't, leave me a comment and I'll clarify.
I also used this tutorial from Craftster to turn several bottoms into maternity shorts. Very simple instructions with pictures.