Grade Between Sizes

Most pattern companies print multiple size lines on a single pattern piece. Grading means following one size line for part of the pattern, then smoothly transitioning to a different size line at another part.

The most common scenario: you need a size 12 at the bust but a size 16 at the hip. Without grading, you'd either have a bust that gaps or a hip that pulls. With grading, you cut a size 12 at the shoulders and underarm, then blend outward to the size 16 cutting line by the hip level — following a smooth curved line along the side seam.

Tops and blouses that end at or above the hip usually only need one grade — bust to hip — along the side seam below the underarm. If the top ends at the natural waist or has no hip ease (like a fitted peplum), you only grade to the hem.

Dresses may need two grade transitions: bust to waist, then waist to hip. Each transition happens along the side seam, with the grade completing at the relevant level. If your waist size falls between your bust and hip sizes, the grade line passes smoothly through it.

Pants and skirts are sized by hip, so the grade tool doesn't apply — use the Pants Size Finder or Skirt Size Finder instead, then adjust the waist separately.

A good grade line has no kinks — it curves smoothly from one size cutting line to the other. The transition should start and end on an existing size line (not in between), and it should cross from one line to the other gradually over the full blend zone length.

Use a French curve or a flexible ruler(sometimes called a curved rule or ship's curve) to draw the transition. Avoid connecting the dots with a straight line — the side seam of a garment is always slightly curved, and a straight grade will create a flat spot that pulls when worn.

After drawing, measure the seamline (5/8" or 1.5 cm inside the cutting line) at bust, waist, and hip and compare to your body measurement plus ease. If any point is off by more than ⅛", adjust the blend line before cutting.