Pattern Grading Calculator

Estimate a pattern measurement at a different size using a per-size grade increment.

The pattern's own measurement (like bust or waist) at the size you're grading from.
How much that measurement changes from one size to the next — check the pattern's size chart if you're unsure.
How many sizes larger (positive) or smaller (negative) you're grading to.

Hold Pattern Pieces in Place

Pattern weights let you trace and true graded lines without pins distorting the paper or fabric underneath.

What a grade rule is

Pattern companies size a garment by drafting one base size, then "grading" it up and down by a fixed increment per measurement, per size — the grade rule. A common misses-sizing grade rule is around 1" per size at the bust/waist/hip circumference, but the exact number varies by brand, size range, and even by measurement (sleeve length grades by a much smaller increment than bust circumference).

How this calculator works

New measurement = base measurement + (grade rule × number of size steps). Moving down in size uses a negative number of steps and subtracts instead.

Where to find your actual grade rule

If the pattern includes a size chart with measurements for multiple sizes, subtract two adjacent sizes' measurements to get the real grade rule for that specific pattern and measurement, rather than guessing — grade rules for children's patterns, petite ranges, and plus-size ranges in particular often differ from standard misses grading.