A rectangle body shape has bust, waist and hip close together. In the FFIT system that means bust and hip within 3.6 inches (9.1 cm) of each other, without the waist difference an hourglass needs. It is one of the most common shapes, and one of the most badly served by generic advice — usually some version of “create curves”, as if curve were the only acceptable goal.

You have two good options, and they suit different moods and occasions. You can lean into the straight line, or you can build curve on purpose. What doesn’t work is the half-measure in between.

Option one: lean into the line

A straight outline is the easiest to dress with clean, architectural clothes. Pieces that look fussy on curvier shapes look intentional on yours.

  • Column dresses and shifts. They fall straight from shoulder to hem without fighting anything.
  • Straight-cut coats and longline blazers. The unbroken vertical line is the whole point.
  • Monochrome. One color head to toe emphasizes length and simplicity.
  • Minimal tailoring. Straight trousers, collarless jackets, crisp shirts.

This is the option fashion editorials use most, for a reason: on this outline, simple clothes look expensive.

Option two: build the curve

If you want the impression of a waist, build it with construction, not with fit alone. A tight waistband on a straight outline has nothing to grip, so it looks like strain rather than shape. These do the work instead:

  • Peplums. The flare below the waist creates a hip, so the waist looks narrower by contrast.
  • Bias-cut skirts and dresses. Fabric cut on the diagonal drapes and moves, adding curve.
  • Wrap fronts. The diagonal line suggests a waist where the wrap crosses.
  • A belt over a looser layer. Belting a blousy top or a soft dress gathers fabric above and below the belt, creating curve on both sides.
  • Horizontal interest at shoulder and hip. A cuffed sleeve, a wide collar, a patch pocket at the hip — detail at both ends implies a waist between them.

By garment

Tops

Wrap tops, peplum tops and anything that blouses over a waistband all add shape. If you’re going for the straight line instead, choose crisp shirts and fine knits with a clean, even hem. Avoid tops that cling all the way down with no structure — they show the straight line without making a point of it.

Bottoms

Wide-leg and A-line skirts add width below the waist, which makes the waist read narrower. High-rise straight jeans work with either approach. Very low-rise, skin-tight bottoms are the least flattering choice: they emphasize the absence of a waist without offering anything instead.

Dresses

Choose a side. A column or shift for the clean look; a wrap, peplum or belted fit-and-flare for curve. Shapeless sack dresses with no waist and no structure do neither.

Outerwear

Straight longline coats suit the outline naturally. For curve, look for belted trench coats and jackets with a defined waist seam.

Fabrics

Fluid fabrics — silk, viscose, jersey cut on the bias — add movement and suggest curve. Crisp fabrics — poplin, structured wool, denim — emphasize clean lines. Both work. Thin, clingy knits with no drape tend to be the least forgiving.

The alteration that matters most

For most shapes the key alteration is taking something in. For a rectangle it is shortening. With little waist suppression to work with, the length of hems and sleeves does more than anything else to separate a garment that looks tailored from one that looks borrowed. A sleeve that ends exactly at the wrist bone and trousers that just graze the shoe will do more for you than any amount of nipping in.

Common mistakes

  • Cinching hard over a fitted garment. It looks like strain, not shape.
  • Hiding in oversized clothes. Oversized can look great on purpose, but loose clothes that aren’t designed to be oversized just add width.
  • Avoiding belts entirely. A belt over a softer layer is one of the best curve-building tools you have. It’s the tight belt over a fitted garment that fails.

Not sure whether you’re a rectangle or a near-hourglass? The difference is a few inches at the waist. The body shape calculator shows exactly where your numbers fall.