What is grading between sizes in sewing?

Grading between sizes means blending two different size cutting lines on a pattern — for example, cutting a size 14 at the bust and tapering to a size 12 at the waist. This is done by drawing a smooth curved line that transitions between the two size lines.

When do I need to grade between sizes?

You need to grade between sizes when your body measurements fall in different size categories. For example, if your bust measures a size 14 but your waist measures a size 10, grading between sizes will give a better fit than cutting a single size.

What is the difference between grading and alterations?

Grading adjusts size along the side seams (or other seams) to accommodate different measurements. Alterations address shape differences — like a full bust adjustment (FBA), swayback correction, or a sway-forward shoulder. Both may be needed for a well-fitting garment.

How do I draw a smooth line when grading between sizes?

Use a curved ruler (hip curve or French curve) to blend the two size lines. Start at the larger size line, taper gradually over 2–3 inches, and arrive smoothly at the smaller size line. Avoid sharp angles or steps, which would create distortion in the finished garment.

How to Grade Between Sizes in Sewing Patterns

Most people's bodies do not fit neatly into a single pattern size. Grading between sizes — blending two cutting lines on the same pattern — is the standard technique for getting a better fit without complex alterations.

What Is Grading?

Grading means drawing a new cutting line that transitions smoothly from one size to another along the same seam. For example, if you cut a size 14 at the bust but need a size 10 at the waist, you draw a curved line that starts at the size 14 bust line and curves inward to the size 10 waist line.

Grading is done along the side seams (and sometimes the center front/back seams) before cutting the fabric. It requires a multi-size pattern — one that prints several size lines on the same tissue — which is standard for most US sewing patterns.

When to Grade

Grade between sizes when your bust, waist, and hips fall in different size ranges. To find out, take your measurements and compare them to the brand's size chart:

How to take your measurements →Size Finder tool →

If all three measurements (bust, waist, hip) fall in the same size range, cut a single size and adjust only if you have a unique figure characteristic (broad shoulders, long torso, etc.).

How to Grade Step by Step

1
Measure yourself accurately
Take your bust, waist, and hip measurements following the guide for your brand. Write the numbers down before comparing.
2
Identify which size each measurement falls in
Compare to the size chart on your pattern envelope. Note if your bust is a size 14 but your waist is a size 10 — that gap of two sizes is very common and easy to grade.
3
Mark the larger size at the appropriate area
On the pattern tissue (or a tracing), mark the larger size line where that measurement dominates — bust line for tops, hip line for skirts.
4
Draw a smooth curved line between sizes
Use a curved ruler to blend the transition. The line should taper gradually over at least 2–3 inches. Avoid sharp steps or angles. A smooth curve distributes the size change evenly across the seam.
5
Repeat on all matching seam pieces
The front and back side seams must be graded identically so they still match up when sewn together. Check notch placement after grading.

Common Grading Scenarios

Situation	Approach
Larger bust, smaller waist and hips	Cut the larger size at the bust, taper to the smaller size at the waist. Keep the hip at the smaller size.
Larger hips than bust	Cut the smaller size at the bust, blend to the larger size at the hip. Taper back in at the hem if needed.
Proportional figure, one size larger overall	Cut the same size throughout. No grading needed — consider a single-size cut and adjust ease instead.
Standard waist, full hips	Cut your waist size at the waist seam, blend outward to the hip size at the fullest hip. Blend back for the hem.

Grading vs Alterations

Grading adjusts size along seam lines. It addresses differences in measurement — a larger hip or a smaller waist than the printed size. Grading happens before you cut.

Alterations address shape differences that measurements alone do not capture: a full bust adjustment (FBA) adds width and length for a larger cup size; a swayback alteration shortens the back rise; a broad shoulder adjustment widens the shoulder seam without affecting the sleeve cap.

Most sewists need both: first grade for size, then alter for shape. Make a muslin (test garment in cheap fabric) to check fit before cutting into your good fabric.