Sewing Pattern Sizes vs Store Sizes and How to Measure

A size 14 that fits nobody you know

On the Simplicity misses' chart, a size 14 is drafted for a 36 inch (92 cm) bust, 28 inch (71 cm) waist and 38 inch (97 cm) hip.¹ Butterick's own fitting brochure warns that your pattern size may be one or two sizes larger than the size you usually buy ready-to-wear.² Nothing is wrong with your body or with the pattern; the two systems are built on different measurements.

A store label is a number chosen by the brand, and two brands' size 12s do not have to measure the same. A pattern size is tied to a published table of body measurements. Once you choose from your own tape-measure numbers, the size printed on the envelope is only a label for one row of that table.

Where pattern sizes come from

The major US pattern companies (Simplicity, McCall's, Butterick and Vogue) have long sized their patterns from shared body measurement tables. A 1968 University of Minnesota extension folder notes that all four had adopted revised body measurements approved in November 1967 by the pattern industry's Measurement Standard Committee.⁶ A 1998 brochure published with Simplicity, McCall's and Butterick shows the same Pattern Industry Standards chart for misses' sizes 4 to 26.² The numbers have changed little since: size 16 is still a 38 inch bust, 30 inch waist and 40 inch hip on both the brochure and Simplicity's current chart.¹²

Ready-to-wear manufacturers can draw on other tables. ASTM International publishes D5585, a set of body measurement tables for the adult female misses figure type in sizes 00 through 20, intended as a baseline for designing apparel in that range.³ Its range runs down to 00, so it is plainly a different scale from the pattern chart, which starts at 4 or 6.

Pattern charts also assume a figure type. Simplicity's misses' sizes are drafted for someone about 5 feet 5 inches to 5 feet 6 inches (165 to 167 cm) tall, with a B cup, meaning a 2 inch (5 cm) difference between bust and high bust.¹

How to take your measurements

Use a soft tape measure that has not stretched, and wear the underwear you plan to wear with the garment. A helper makes the job easier if you have one. Measure snug but not tight, with the tape level all the way around.⁵ Tie a piece of narrow elastic or string around your waist first and leave it there; it settles at your natural waist and gives you a fixed line to measure from.⁵⁶

Write down every number with the date. Simplicity suggests remeasuring about every six months, because bodies change.¹ If your thighs are wider than your hips at the usual hip line, measure both and use the larger figure.⁵

Ease: the difference between your body and the garment

Ease is the extra room a garment has beyond your body measurements. Pattern makers divide it into two kinds. Wearing ease is the minimum room you need to breathe, sit and move. Design ease is the additional fullness that gives the style its look, such as a loose shirt or a full skirt.²

For woven fabrics, the pattern industry builds in about 2 to 3 inches of minimum ease at bust and hip, then adds design ease on top.² A New Mexico State extension guide suggests 3 to 4 inches at the bust and 2 to 4 inches at the hips for a fitted garment, and gives the example of a pattern for a 36 inch bust with 2 1/2 inches of ease measuring 38 1/2 inches across the pattern.⁴ Close-fitting knits and swimwear may have no wearing ease at all, because the fabric stretches.¹

So do not choose a pattern size from the finished garment measurements alone. The body measurement chart already accounts for ease. Pick by body measurements, then check the finished measurements to see how loose the style will be.

Reading the back of the pattern envelope

The back of the envelope is a planning sheet. Expect to find a back view of the design, a size and body measurement chart, a yardage chart, a list of notions (zippers, buttons, elastic, interfacing) and suggested fabrics.⁷ The fit is also described in words. Butterick uses terms running from close-fitted through fitted, semi-fitted and loose fitting to very loose fitting.²

Finished bust and hip measurements are often printed on the tissue pattern pieces themselves, not the envelope.² Compare those numbers with a garment you already own and like. If your favorite shirt measures 41 inches around the chest and the pattern's finished bust is 44 inches, you know the new shirt will be noticeably roomier.

Simplicity's size advice depends on the garment: choose tops, dresses, jackets and coats by bust; trousers and most skirts by hip; and a skirt that is loose over the hip by waist.¹ If your bust minus high bust is 2 1/2 inches or more, use your high bust in place of the bust figure when you read the chart, then enlarge the bust area.¹

Worked example: 36, 30, 40

Take someone with a 36 inch bust, 30 inch waist and 40 inch hip, and a high bust of 34 inches. Here is how they would read the Simplicity misses' chart.¹

• For a fitted dress: start from size 14 at the bust, because shoulders and neckline are the hardest areas to alter. Then grade (blend from one size line to another) out to the size 16 line at the waist and hip. On a multi-size pattern, draw a smooth curve from the 14 cutting line at the armhole to the 16 line by the waist, and follow the 16 line down through the hip.
• For trousers or a fitted skirt: use size 16, chosen by hip. The waist also matches 16, so no grading is needed.
• For a loose top: size 14 by bust. The design ease will cover the waist and hip.
• Check the result against finished measurements. If the tissue says the size 16 hip is 44 inches, they will have 4 inches of ease there, comfortable for woven trousers.

The same numbers help with ready-to-wear. If a shop dress fits the bust but strains at the hip, they know the hip is two pattern sizes larger than the bust, so they should buy for the hip and take in the upper body, which is usually easier than letting out. See taking in side seams and adjusting darts.

Using measurements to alter ready-to-wear

Lay a garment flat, measure across it, and double the number to get the full circumference. Subtract your body measurement and you know the ease you have. A pair of trousers that measures 21 inches across the hip (42 inches around) gives a 40 inch hip 2 inches of ease, on the snug side for a woven fabric.

To get more room, check the seam allowances first. If there is at least 5/8 inch (15 mm) inside, a seam can often be let out; see letting out a seam and when you cannot let it out. Waist changes on trousers are covered in adjusting a waistband, and the full fitting process is in the fit guide.

Common mistakes

• Buying your shop size. Measure and use the chart, even if the number feels too big.
• Measuring over thick clothes or pulling the tape tight. Both throw the result off by an inch or more.
• Choosing by finished measurements. Body measurements first, finished measurements second.
• Measuring hip at the hip bones. The chart means the fullest part of the seat, which is usually lower.
• Picking the largest of your sizes for everything. A dress cut for the hip everywhere will gape at the neck and shoulders.

Keep a small card in your sewing box with your bust, high bust, waist, hip, back waist length and inseam, plus the date. Take it with you when you shop for patterns and you can read any envelope chart on the spot.