The Basic Process for Adding Pockets to Trousers
Sewing pockets into trousers means cutting openings in the fabric, attaching pocket bags (the fabric that forms the inside pouch), and finishing the edges so they do not fray. The most common method is a side seam pocket, which sits along the inner seam of the leg and is hidden when you wear the trousers. You will need the trousers themselves, two pieces of pocket fabric (usually cotton or linen), thread that matches your trousers, a needle or sewing machine, scissors, pins, and a measuring tape.
The work takes two to four hours depending on whether you use a machine or hand-sew, and whether the trousers are already made or you are building them from a pattern. If the trousers are finished, you will need to unpick part of the seam to insert the pocket. If you are making trousers from scratch, you sew the pocket in before you close the side seam.
Key Takeaways
- Side seam pockets are the easiest to add because they sit along an existing seam and require only one opening in the trouser fabric itself.
- Pocket bags are cut from a separate fabric and sewn to the opening, then the two bags are sewn together to form a closed pouch inside the leg.
- If your trousers are already finished, you unpick 4 to 6 inches of the side seam where you want the pocket to sit, then sew the pocket in and re-close the seam.
- Pressing with an iron after each major step keeps the pocket flat and the edges crisp, which prevents bunching when you wear the trousers.
Measuring and Marking the Pocket Opening
Decide where you want the pocket to sit. On most trousers, the opening starts about 4 inches below the waistband and runs 5 to 7 inches down the leg. Mark this with a fabric pencil or tailor's chalk on the inside of the trouser leg, drawing a rectangle that is about 5 inches tall and 1 inch wide. This rectangle is the opening where your hand will go in.
If the trousers are already sewn, use a seam ripper to carefully cut and remove the thread along the side seam where your pocket opening will be. You only need to unpick the length of the opening plus 1 inch on either side — about 7 inches total. Do not unpick the entire seam. Press the opened seam flat with an iron so the fabric lies smooth.
If you are making trousers from a pattern, the pattern will tell you where to mark the pocket opening. Follow those marks exactly, as they are positioned to balance the trousers visually and sit at a comfortable height for your hand.
Cutting and Preparing the Pocket Bags
Cut two identical pieces of pocket fabric, each about 8 inches long and 5 inches wide. These are your pocket bags. If you are using a pattern, it will include a pocket bag template — trace it and cut along the lines. If you are improvising, make sure both pieces are exactly the same size and shape.
Finish the edges of each pocket bag to prevent fraying. You can do this by sewing a zigzag stitch along each edge with a machine, or by hand-sewing a whip stitch around the perimeter. Alternatively, use pinking shears to cut the edges at an angle, which slows fraying. Press both finished bags flat with an iron.
Place the two pocket bags with their right sides (the pretty sides) facing each other. Pin them together along three sides, leaving one short end open. This open end will be sewn to the trouser opening. Sew along the three pinned sides using a 1/2-inch seam allowance, then turn the bag right-side-out through the open end and press it flat. You now have a closed pouch with one open edge.
Attaching the Pocket Bag to the Trouser Opening
Position the open edge of the pocket bag along the marked opening on the inside of the trouser leg. The raw edges of the bag should align with the raw edges of the trouser opening. Pin the bag in place, making sure it sits flat and does not twist.
Sew the pocket bag to the trouser opening using a 1/2-inch seam allowance. Sew slowly and carefully, keeping the stitches straight and even. If you are hand-sewing, use a backstitch for strength. If you are using a machine, use a straight stitch and backstitch at the beginning and end to lock the thread. Sew all the way around the opening, then remove the pins.
Repeat this step on the other side of the opening with the second pocket bag. You now have two pocket bags, one on each side of the opening, both sewn to the trouser fabric. Press the seams flat with an iron, pressing from the inside of the leg.
Closing the Side Seam and Finishing the Pocket
If you unpicked the side seam to insert the pocket, you now need to re-close it. Fold the trouser leg so the side seam is aligned, with the pocket bags tucked inside. Pin the seam closed, starting above the pocket opening and working downward. Make sure the pocket bags do not get caught in the seam.
Sew the side seam closed using a 1/2-inch seam allowance, using the same stitch type you used for the pocket bags. Start sewing above the pocket opening, sew down to where the pocket opening begins, then skip over the opening (do not sew through the pocket bags), and resume sewing below the opening. Backstitch at the beginning and end of each section to lock the thread.
Once the side seam is closed, sew the two pocket bags together along their sides. Fold the bags so they sit one behind the other inside the leg, and sew along the side edges using a 1/2-inch seam allowance. This keeps the bags from shifting and separates them so they do not bunch together. Press the entire pocket area with an iron from the inside of the leg.
Reinforcing the Pocket Opening for Durability
The corners of the pocket opening take the most stress when you reach into the pocket, so reinforce them to prevent tearing. Sew a small triangle or box at each corner of the opening, using a tight stitch. Start at one corner, sew a small square about 1/2 inch on each side, then sew diagonally across the square and back. This creates a reinforced area that can handle repeated use.
Alternatively, use a bar tack — a series of tight stitches sewn back and forth across the corner. Sew 8 to 10 stitches in the same spot, moving only 1/4 inch along the edge with each pass. This creates a dense, strong area that resists tearing.
Press the entire pocket one final time with an iron, pressing from the inside of the leg. This sets all the seams and gives the pocket a finished appearance.
Common Mistakes and How to Avoid Them
The most common mistake is sewing the pocket bags to the wrong side of the trouser opening. The raw edges of the bags must face outward, toward the raw edges of the trouser fabric. If you sew them backward, the seams will be visible on the outside of the trousers. Check the orientation before you pin and sew.
Another mistake is making the pocket bags too small. If the opening is 5 inches tall, the pocket bag should be at least 8 inches long so it extends well below the opening. A shallow pocket is uncomfortable to use and looks unfinished. Measure twice before you cut.
Bunching happens when the pocket bags are not sewn together along their sides, or when they are sewn together but not pressed flat. Always sew the bags together and press them with an iron after sewing. This keeps them flat and prevents them from shifting when you use the pocket.
If you are working on finished trousers and the side seam is a decorative topstitch (a visible line of stitching on the outside), you will need to re-sew that topstitch after you close the seam. Use thread that matches the original topstitch and sew along the same line, using the same stitch length.
Frequently Asked Questions
Can I add pockets to trousers that are already hemmed?
Yes. You unpick the side seam where you want the pocket, insert the pocket bags, re-close the seam, and then re-sew any topstitching. The hem stays in place. The only extra work is unpicking and re-sewing the seam, which takes an extra 30 minutes.
What fabric should I use for pocket bags?
Use a lightweight cotton, linen, or cotton-linen blend that matches or complements the trouser fabric. Avoid heavy fabrics like denim or canvas, which create bulk inside the leg. If the trousers are a light color, use light-colored pocket fabric so it does not show through.
How deep should the pocket be?
A comfortable pocket is 6 to 8 inches deep, measured from the opening downward. This is deep enough to hold a hand or a small object without the item falling out. If you make it shallower than 5 inches, it will feel cramped. If you make it deeper than 10 inches, it may sag or bunch.
What if I want patch pockets instead of side seam pockets?
Patch pockets are sewn on top of the trouser fabric rather than hidden inside the seam. Cut a rectangle of fabric, fold and press the edges inward, pin it to the outside of the trouser leg, and sew it down with a straight stitch or decorative stitch. Patch pockets are faster to sew but more visible, so they work best on casual trousers.
Do I need a sewing machine, or can I hand-sew the entire pocket?
You can hand-sew the entire pocket using a backstitch, which is strong enough for regular use. Hand-sewing takes longer — about 4 to 6 hours instead of 2 to 3 — but the result is the same. Use thread that matches the trousers and sew with small, even stitches for the neatest appearance.