Adjusting the size of your own clothes is not as difficult as it may first appear. You can make many different types of adjustments to clothing before requiring the assistance of a professional tailor, such as increasing the size of a pair of jeans. Although sizing jeans down tends to be easier, since it is less work to take away fabric than to add fabric, you can make some simple adjustments on a pair of jeans to increase the size. Some of the most common increases made to jeans are in the waistband, leg length and leg width measurements.
Determine how much extra fabric needs to be added to the waistband. Divide this measurement in half, then add 1 inch to the new measurement.
Make a cut on each side of your waistband so that the jeans gape wide enough to fit you.
Measure the length of the gaps and add 1/2 inch.
Cut two triangles from the denim material that are as tall as the length measurement and as wide at the base as your width measurement from Step 1.
Add an extra 1/2 inch to the height of the triangles at the base. Fold this 1/2 inch under and sew it in place.
Lay one side edge of a triangle against the side edge of a gap, with the right sides of the denim together. Sew 1/2 inch away from the edge.
Repeat Step 6 on the other side of the triangle, then do the same to the gap on the other side of the waistband.
Measure up 1/2 inch from the hem stitching on the bottom of each leg. Cut the hems off the legs at this point and put them aside.
Measure the distance you need to add to the legs, and the width of the existing legs. Add 1 inch to the width, and 1 1/2 inches to the length. Cut four rectangles from the denim fabric that are as long and wide as these measurements.
Lay two of the rectangles with the right sides together, and pin the sides together. Sew the sides, 1/2 inch away from the edges. Do the same to the other two rectangles.
Turn the jeans legs inside out. Pin the bottom edges of the jeans legs to the top edges of the extension pieces from Step 4, lining up the side seams. Sew 1/2 inch away from the edges.
Pin the hem pieces to the bottom edges of the legs. Sew along the original stitching line.
Measure the amount by which you need to increase the leg width, and add 1 inch.
Cut two rectangles of fabric that are this wide, and as long as the jeans legs plus 2 inches. Turn under 1 inch at the top and bottom of each rectangle and sew them in place.
Cut apart the jeans at the side seams on the outside of the legs.
Pin one edge of a rectangle to the cut edge of a jeans leg, with the right sides together. Sew 1/2 inch away from the edges. Do the same to the other side of the rectangle.
Repeat Step 4 on the other jeans leg.
Do not attempt to add more than a few inches to the measurements, particularly the waistband measurement. If you need a size that is much larger than your existing pair of jeans, you will need to spring for a new pair of jeans.