The Inverted Triangle, and the cuts that follow from it.

Off the rack, shirts and jackets are cut for a gentler taper than yours, so the cloth that fits your chest arrives with a waist meant for a man who narrows less.

That gap is behind most of what goes wrong for you in a fitting room.

The first job is to add nothing across the top. Shoulder pads, flapped chest pockets, a dropped shoulder: each one lands on the widest part of you, and the wider the top reads, the steeper the fall below it looks. What works up there takes its shape from you: a soft shoulder, a V at the neck, a front that opens.

The second job is the one men miss. The lower half needs presence: room through the seat and thigh and a leg that keeps that width to the shoe, so the trousers answer the chest instead of disappearing under it. What counts is ease where your seat and thigh are, more than width at the hem.

Where a hem lands decides the rest. A ribbed band at the hip, the finish of a bomber, cinches the hem where you are narrow and leaves the chest to billow above it. A hem that falls straight past the hip, on an open cardigan or a knee-length coat, carries the line of the shoulder on down the body instead. The list below is built on those two jobs.

This is where an inverted triangle loses the most money, so buy slowly.

A suit sold as a set is cut on the standard 6-inch drop and yours is bigger, so the jacket that fits your chest comes with trousers too big in the waist. Buy jacket and trousers as separates where a maker sells them that way.

Go soft at the shoulder. An unconstructed blazer or a soft textured suit lets your own shoulder be the structure. A constructed classic suit at standard padding has the padded-shoulder blazer's problem, and the rules refuse it on this shape. Ask to see the shoulder: with the padding taken back to a layer of canvas, the seam stays where your shoulder ends, and that is a different jacket, one that works. Evening wear follows the same rule, and the catalog's tuxedo, built on a padded shoulder, comes back Skip here.

Single-breasted, with a notch lapel of ordinary width. A double-breasted suit runs its lapels wide across the chest and adds a second horizontal at the button stance, and a wide peak lapel points up and out toward the shoulder. Both give the top half help it does not need.

For trousers, pleated suit trousers or a straight leg with room through the thigh, cut at the one rise your page sets for you.

The buying rule saves the most grief. Buy for the shoulder, then have the waist and back taken in. Taking a jacket in is routine work, while the shoulders, in the words of one suit maker's alteration guide, are "nearly impossible to alter once constructed."

Your shape reads width, and on this frame it comes down to two instructions: add nothing to the shoulder, give the lower half room. Your line reads edges, whether your bone structure, the line of your shoulders and your features come out sharp, medium or soft. A steep drop from shoulder to waist is a ratio, and a ratio says nothing about the bone it was measured over.

So two inverted triangles can need different jackets. Both need a shoulder that adds nothing. With a sharp line it is the knee-length straight coat, structure carried in the length and a clean edge rather than a pad. With a soft line it is the unstructured blazer, which takes its shape from you. Under them, the sharp line's top is a crisp piqué polo and the soft line's a henley, and the table below runs the same split through the rest of the wardrobe.

The sample analysis shows the two checks working apart. Filip Poláček, a trapezoid with a medium line, gets the structured classic suit as a Wear for his build, "Shoulder and body are cut the way you are built, so it closes without strain," and the soft textured suit as a Skip for his line, "The rounded, soft seams blur a frame that reads better with a clean edge." On an inverted triangle the build turns against the structured suit first, and the line rules on what is left.

Neither reading predicts the other: an inverted triangle is not automatically a sharp line, and no line belongs to a shape. Above both sit your body details.

Body details are applied after the shape and win wherever the two disagree.

On this frame, three of them change the most verdicts.

• Your rise. Your page sets one rise for you, and any trouser cut at another height is a Skip, whatever its leg does. That splits this list in two: the pleated trousers and the wide-leg sit high, the straight trousers with room and the straight denim at mid rise. The sample analysis, at a mid rise, turns down the high-rise wide-leg, "The wide leg starts from a waistband set at the wrong rise for you," and keeps the straight trouser with room. A shorter leg or a longer torso points to the high pair.
• Narrow shoulders. A man can measure narrow at the shoulder in absolute terms and still drop steeply to a small waist. Then the rule turns around and narrow shoulders count in favor of a sharp shoulder, which brings the padded-shoulder blazer back into contention, judged by your line like any other jacket.
• Broader thighs. They refuse any trouser without room at the thigh, and every bottom that is skin-tight or bulky there. The four trousers on this page are all cut with thigh room and stay. The catalog's regular chino is not, so for you the straight denim and chino card narrows to the denim.

The rules also cover a fuller midsection, a stronger seat and a plus-size frame, and each one applies only when your answers say it should.