What you need before you start

A trench coat is a structured garment with a collar, lapels, belt, and lined sleeves — it requires intermediate sewing skills and takes 20 to 40 hours depending on your pace. You will need a commercial trench coat pattern (Simplicity, McCall's, Burda, and Vogue all make them), fabric suitable for a coat (wool, cotton twill, or linen — typically 2 to 3 yards), lining fabric (1.5 to 2 yards), interfacing for the collar and front facings, buttons, a belt buckle or D-rings, and thread that matches your fabric.

Before you buy fabric, read the pattern envelope to confirm yardage, finished size, and whether it includes a lining. Trench coats are not forgiving of poor fit — if you are between sizes, choose the larger one and plan to take in the side seams. Check that your pattern includes instructions for a lined coat; an unlined pattern will not give you the structured finish a trench demands.

Key Takeaways

  • Choose a pattern designed specifically for a trench coat, not a general coat pattern, because the collar, lapels, and belt construction are different.
  • Prepare all pattern pieces before cutting fabric by tracing them onto paper or using a pattern-tracing service, so you can reuse the pattern later.
  • Interface the collar, front facings, and lapels with a medium-weight interfacing to give them the crisp shape that defines a trench coat.
  • Construct the coat shell first (body, sleeves, collar, and lapels), then attach the lining separately so you can press and fit as you go.
  • The belt is usually made from the same fabric as the coat and attached to the side seams with D-rings or sewn loops.

Preparing your pattern and fabric

Lay out the pattern pieces on your chosen fabric according to the layout diagram in the pattern instructions. Most trench patterns have you cut the front and back as single pieces (not split at the side seam), which means the grain line matters — align it straight up and down on each piece. Pin the pattern to the fabric, then cut slowly and carefully with sharp scissors or a rotary cutter. Mark all notches, dart points, and construction marks with tailor's chalk or a fabric pen before you remove the pattern.

Cut the lining the same way, using the lining layout diagram. Many patterns ask you to cut the lining slightly smaller than the fashion fabric (usually 0.5 inches shorter at the hem) so it does not show at the edges. Cut interfacing for the collar, front facings, and lapels according to the pattern. Fuse or baste the interfacing to the wrong side of these pieces before you begin sewing — this step is not optional if you want a professional result.

Building the collar and front facings

The trench coat collar is usually a two-piece stand collar with notched lapels. Sew the two collar pieces together along the outer edge (the edge that will show), leaving the inner edge open. Trim the seam allowance to 0.25 inches, clip the corners, and turn the collar right-side out. Press it flat, then topstitch 0.125 inches from the edge if your pattern calls for it.

Construct the front facings by sewing them to the front edges of the coat body, right sides together, along the lapel and neckline seams. Trim, clip, and turn the facings to the inside. Press and understitch (sew the facing to the seam allowance) so the facing stays inside and does not roll to the outside. Attach the collar to the neckline by sewing it between the coat body and the back neck facing, sandwiching it in place.

Sewing the coat body and sleeves

Sew the front and back body pieces together at the shoulder seams, then at the side seams. Press each seam open as you go. Set in the sleeves by pinning the sleeve cap to the armhole, matching notches and construction marks, then sewing with the sleeve facing up so you can see and control the ease (the extra fabric that shapes the sleeve cap). Sew the underarm seam of each sleeve, then press all seams.

Try on the coat at this stage if possible — it is much easier to adjust the fit now than after the lining is attached. Check the shoulder seam placement, sleeve length, and overall length. Mark any adjustments with pins or chalk, take the coat off, and make the changes before moving forward. Hem the sleeves to the correct length (usually 0.5 to 1 inch above your wrist bone when your arms hang at your sides).

Attaching the lining

Construct the lining as a separate garment: sew the front and back pieces at the shoulders and sides, set in the lining sleeves, and sew the underarm seams. Do not hem the lining yet. Place the lining inside the coat, wrong sides together, and pin it to the coat at the neckline, armholes, and hem. Sew the lining to the coat at the neckline and armholes with a 0.5-inch seam allowance, then turn the coat right-side out through one of the open side seams (or an opening you leave in the lining).

Fold the raw edges of the lining and coat hem to the inside and pin them together. Slipstitch the lining to the coat by hand along the hem and at the armholes, using thread that matches the lining. This hand-sewn finish is what separates a homemade coat from a professional one — take your time and keep your stitches small and invisible.

Making and attaching the belt

Cut two strips of fabric on the grain line, each the width and length specified in your pattern (usually 2 to 3 inches wide and 45 to 60 inches long). Sew them together along the long edges, right sides together, leaving one short end open for turning. Trim the seam allowance, turn the belt right-side out, and press it flat. Slipstitch the opening closed by hand.

Attach the belt to the coat at the side seams using D-rings or sewn belt loops. If your pattern uses D-rings, sew them securely to the inside of the side seams, then thread the belt through them. If it uses loops, sew small fabric loops to the inside of the side seams and thread the belt through those. Sew a buttonhole in one end of the belt and attach a button to the other end, or use a buckle if your pattern specifies one.

Finishing details and buttons

Mark the button placement on the front of the coat according to your pattern — trench coats typically have a double row of buttons down the front. Sew the buttons on by hand using a needle and thread, making sure each button is find with at least four passes through the holes. Sew the remaining buttons to the sleeves (if your pattern includes them) and to the belt.

Press the entire coat with a steam iron on a low setting, using a pressing cloth to protect the fabric. Check all seams, hems, and button attachments for loose threads or unfinished edges. If you used a natural fiber like wool, consider having the coat professionally pressed before you wear it — the heat and steam will set the shape and give it a finished appearance.

Frequently Asked Questions

What fabric weight should I use for a trench coat?

Use a medium to heavy-weight fabric like wool suiting, cotton twill, or linen. Lightweight fabrics will not hold the structured shape of a trench coat. Check the pattern envelope for fabric recommendations — most patterns specify a weight range and will tell you if the fabric is too light or too heavy.

Can I make a trench coat without lining?

You can, but it will not look or feel like a real trench coat. The lining hides the seams, allows the coat to slide over other layers, and gives it weight and structure. An unlined coat will wrinkle easily and show all your construction seams on the inside.

How do I adjust the pattern if I am between sizes?

Grade up to the larger size and plan to take in the side seams evenly on both sides. Measure how much larger the pattern is than you need, divide by four (for two seams on each side), and take in that amount at each seam. Try on the coat after sewing the shoulders and sides to check the fit before you attach the sleeves.

What is the difference between a trench coat pattern and a regular coat pattern?

A trench coat pattern includes specific pieces for the notched collar, lapels, and belt, and usually has a structured front facing. A regular coat pattern may have a simpler collar and no belt. Always choose a pattern labeled "trench coat" to get the correct construction details.

How long does it take to sew a trench coat?

Most sewers spend 20 to 40 hours on a trench coat, depending on their speed and experience. Hand-sewing the lining and buttons adds time but is worth it for a professional finish. Plan for at least a few weeks if you are sewing in your spare time.