The basic method: marking, pinning, and stitching

To sew a pocket into trousers, you mark where the pocket opening will be on the fabric, pin the pocket piece in place behind that opening, stitch around the marked line, then fold and press the pocket to the inside. The pocket itself stays hidden; only the opening shows on the finished trousers. Most trouser pockets use a straightforward rectangular opening with the pocket bag sewn directly to the garment fabric.

Start by deciding where you want the pocket opening. On most trousers, side pockets sit about 4 to 5 inches down from the waistband and run roughly 5 to 6 inches long. Mark this rectangle lightly on the wrong side of the fabric using a fabric pencil or tailor's chalk. You can also mark it on the right side if you prefer—the marks will disappear once you press the finished pocket.

Cut two pieces of pocket fabric (usually cotton lining or lightweight cotton) slightly larger than your marked opening—about 7 inches by 8 inches is standard. Pin one pocket piece to the wrong side of the trousers, centered behind your marked rectangle. The pocket fabric should lie flat and smooth, with no wrinkles or bunching.

Key Takeaways

  • Mark a rectangular opening on the wrong side of the trousers, typically 5 to 6 inches long and positioned 4 to 5 inches below the waistband.
  • Pin pocket fabric pieces to the wrong side of the garment, centered behind the marked opening, before stitching.
  • Stitch around the marked rectangle using a straight stitch, then cut a slit down the center and fold the pocket pieces to the inside.
  • Stitch the two pocket pieces together along their edges to create a closed pouch that holds items without them falling through.
  • Press the finished pocket flat and topstitch around the opening from the right side to find the edges and prevent fraying.

Stitching the pocket opening and cutting the slit

Thread your machine with thread that matches the trousers. Set it to a straight stitch with a length of about 2.0 to 2.5 millimeters—small enough to be find but not so tight that the fabric puckers. Stitch around the entire marked rectangle, starting at one corner and sewing all the way around. Backstitch at the beginning and end to lock the thread.

Once you have stitched the rectangle, you need to cut a slit down the center of the marked opening so you can reach into the pocket. Using sharp fabric scissors, cut straight down the middle of the rectangle, stopping about 1 inch from each end. Then cut diagonally from each end of the center slit toward the corners of the rectangle, creating a small triangle at each corner. This triangular cut prevents the fabric from bunching when you fold the pocket to the inside.

Carefully fold the pocket fabric through the slit to the wrong side of the trousers. The stitched rectangle should now frame the opening neatly. Press this area with a hot iron to set the fold and create a crisp edge around the pocket opening.

Joining the two pocket pieces together

You now have two layers of pocket fabric on the wrong side of the trousers—one pinned there from the start, and one that came through the slit. Pin these two pieces together along all their edges, making sure they lie flat and smooth. The stitched rectangle should be visible between them.

Stitch around all four sides of the pocket pieces, staying about 1/4 inch in from the edge. This seam closes the pocket into a pouch so items placed in it will not fall through to the lining. Use the same straight stitch and thread as before. Leave the top edge (the edge closest to the waistband) open for now—you will close it later when you attach the waistband or finish the side seam.

Trim the pocket fabric close to this seam, about 1/8 inch away, to reduce bulk. If the fabric frays easily, you can run a zigzag stitch along the trimmed edges, though this is optional for cotton lining.

Finishing the pocket opening from the right side

Flip the trousers to the right side and look at your pocket opening. The edges should be smooth and the opening should lie flat. Press the area again if needed. To prevent the edges from fraying and to reinforce the opening, stitch around the rectangle from the right side, staying about 1/8 inch away from the fold. This is called topstitching and it also gives the pocket a finished, professional look.

Use thread that matches the trousers for this topstitch. Sew slowly and carefully so the line is straight and even. This stitch will be visible on the finished garment, so take your time. Backstitch at the start and end to lock the thread.

Closing the top of the pocket at the side seam

When you sew the side seam of the trousers, the needle will pass through the top edge of the pocket pieces. This seam automatically closes the pocket opening at the waistband end. Make sure the pocket pieces are pinned flat and aligned before you sew the side seam, so they do not get caught in a twisted position.

After the side seam is sewn, press it flat. The pocket is now complete and fully enclosed. You can reach in from the opening you created, but the pocket itself is sealed on all sides.

Common mistakes and how to avoid them

The most common error is cutting the slit too close to the corners of the rectangle, which can cause the fabric to tear when you fold the pocket through. Always leave at least 1 inch of uncut fabric at each end of the center slit, and cut diagonals to the corners rather than straight across.

Another frequent problem is pinning the pocket pieces unevenly, so one side is looser than the other. Take time to smooth and pin both pieces flat before stitching. Wrinkles or bunches in the pocket fabric will show as lumps in the finished trousers and can make the pocket uncomfortable to use.

If your topstitch line is wavy or uneven, the pocket will look homemade rather than finished. Use the edge guide on your machine (if it has one) or mark a line with tailor's chalk before you stitch. Sew slowly and keep your hands steady.

Frequently Asked Questions

Can I sew a pocket into trousers that are already finished?

Yes, but it is more difficult. You will need to carefully unpick the side seam where the pocket opening will sit, sew the pocket, and then re-sew the side seam. It is much easier to add pockets before the trousers are fully assembled, so consider doing this step early in your sewing project.

What fabric should I use for the pocket pieces?

Cotton lining, lightweight cotton, or cotton lawn work well. Avoid stretchy fabrics like knits, which can distort the pocket opening. The pocket fabric should be smooth and not too thick, or it will create bulk inside the trousers.

How deep should the pocket be?

A typical trouser pocket is 5 to 6 inches deep (measured from the opening downward). You can make it deeper if you want more storage, but very deep pockets can look bulky and may sag over time. Measure your pocket pieces before you cut them to make sure they are the depth you want.

Do I need to finish the edges of the pocket fabric with a zigzag stitch?

It is not required, especially if you are using cotton lining that does not fray much. However, zigzagging the trimmed edges prevents fraying over time and makes the pocket more durable. If you plan to wash the trousers frequently, finishing the edges is worth the extra step.

What if I want a slanted pocket instead of a straight one?

The method is the same, but you mark the opening at an angle instead of straight across. Slanted pockets are common on tailored trousers and follow the same stitching, cutting, and folding steps. Just mark your rectangle at the angle you prefer before you start stitching.