Like any other trouser project, capri pants are made by stitching together four mirroring pieces to make the legs and waistband. Capri construction is not just about cutting a pair of trousers off at the mid-calf mark; rather, making capri pants requires creating a flattering leg line for the required length. Regular trousers may taper sharply at the calf and flare at the ankle, but capri pants need to flare at the calf level. Between the complexity of making standard trousers and the added challenge of capri pants, this process can be difficult, but is not impossible.
Decide what pattern you're going to use. You can make capri pants from scratch with a commercial pattern such as Vogue 7717, but you can also make capri pants with a homemade pattern made from a pair of trousers you already own. Choose a pair that fits you well, and make sure that you don't mind ruining the trousers to make pattern pieces.
Put the trousers on. Determine where you would like the hem of your capri pants to fall, measure the distance between the top of one of the pant legs and the desired hem, and write it down.
Take the trousers apart at the seams, giving you four pattern pieces. Decide if you want to keep the pockets. Measure what's left of the seam allowances and mark the amounts down. You may need to add bigger seam allowances when you begin cutting the capri fabric.
Press each pattern piece flat with the iron. Lay the pieces on top of a single layer of the fabric you chose for your capri pants, which should be similar to the fabric of the pair of trousers you made the pattern from.
Pin the pieces to the fabric and adjust the seam allowances by marking them directly onto the fabric with a fabric pencil. Mark the hemline by using your measurement from Step 2, making sure to account for the added seam allowance.
Determine whether you need to make any more adjustments to the hem. If you want to create a flared effect at the hem, add a few inches of width total to the hems, with even amounts distributed to the front and back leg pieces. Draw soft, even diagonals from the edges of the hemlines to the straight line of the leg, creating an identical triangular flare on each leg piece. Add 2 inches to the hem of each leg piece for seam allowances.
Cut the fabric, using the pattern pieces and your own fabric pencil lines as guides. Stitch the back leg pieces to each other at the center back seam, then the front pieces together at the centre front seam. If you are including a zip or button fly, do so now. Stitch the front pieces to the back pieces at the outside seams, right sides together, then stitch them together at the inside seam. Press the seams open, finish and turn.
Attach the waistband to the top of the capri pants, right sides together. Fold the top down and slipstitch it to the inside of the capri pants. Press. Fold the hem allowance under 1 inch, press and fold it under another inch. Stitch the hem and press.