Key takeaways
- Sewing-pattern sizes and ready-to-wear sizes are not directly interchangeable.
- Use the pattern company's measurement chart for that exact pattern or range.
- Check finished garment measurements so you understand the ease and intended silhouette.
- If different parts of your body fall into different sizes, blending between sizes is normal.
- Choose a sensible starting size first, then fit the garment — do not try to solve every fit issue with the size number alone.
Choosing a sewing-pattern size should be a technical decision, not an emotional one. The number printed beside a size line is simply a label. What matters is the relationship between your body measurements, the pattern's body-measurement chart, the finished garment measurements, the fabric and the fit the designer intended.
That is also why the size you sew may be completely different from the size you buy in a shop. The Sewing & Craft Alliance explicitly notes that pattern sizing is not consistent with ready-to-wear, while Simplicity's own sizing guidance tells users to select pattern size from body measurements rather than ready-to-wear size.
How do I determine my sewing pattern size?
Start by taking current measurements over the underwear or base layer you expect to wear with the garment. Keep the tape level and comfortably snug rather than pulling it tight. The most important measurements depend on the garment: bust or chest for many tops and dresses, waist and hip for skirts and trousers, plus lengths and other dimensions where the style requires them.
Then compare those numbers with the body measurement chart supplied by that pattern company. Do not assume that a size 14 from one company equals a size 14 from another. Even within one brand, different blocks or size ranges can use different assumptions.
Why doesn't my sewing pattern size match my shop size?
Ready-to-wear brands use their own commercial sizing systems, and those labels can vary significantly between brands. Sewing patterns also use brand-specific size charts. There is no useful rule that converts a UK shop size directly into a universal sewing-pattern size.
The practical answer is to ignore the label and use the measurements. If your body measurement places you in a pattern size that looks surprisingly different from your normal clothing size, that is not a problem. It simply reflects a different sizing system.
Why should I check finished garment measurements?
The body chart tells you who the pattern is drafted to fit. The finished garment measurement tells you how large the garment will actually be after sewing.
If your bust is 96 cm and the finished garment bust is 104 cm, the garment has 8 cm of total ease at the bust. That 8 cm includes any room needed for movement plus any extra room used to create the design.
This is why finished measurements matter so much. Two patterns aimed at the same body size can have very different finished measurements because one is close fitting and the other is relaxed. Simplicity's pattern-size tutorial recommends looking at both body and finished garment measurements before deciding what to cut.
What is the difference between wearing ease and design ease?
Wearing ease is the room needed for the body to move, sit and breathe comfortably. Design ease — sometimes called style ease — is additional room deliberately used to create the silhouette.
A fitted woven dress needs enough room to move. A loose shirt may contain substantially more design ease. A stretch garment may have very little positive ease or even negative ease, where the finished garment is smaller than the body and relies on the fabric stretching.
There is no single universal ease figure that is correct for every garment. Fabric structure and stretch, garment function and styling all change the answer. That is why I prefer to assess the finished garment measurement rather than follow a generic rule.
What if my bust, waist and hip fall into different sizes?
That is extremely common. Bodies do not follow a single mathematical size line, and a multi-size pattern is specifically useful because it lets you move between size lines.
A common approach is to select the most appropriate starting size for the area that is hardest to alter and then blend smoothly to another size at the waist or hip. Exactly where you start depends on the garment. For example, shoulder and upper-body fit may be more difficult to correct cleanly than taking some width from a side seam.
Do not create a sharp corner where one size meets another. Blend gradually while maintaining the intended seam shape and matching corresponding seam lengths.
Which body measurement should control the size I choose?
Use the measurement most relevant to the garment and follow the pattern company's guidance. Tops, dresses and jackets are usually driven by the upper body, while skirts and trousers often depend more heavily on hip or waist. Some companies advise choosing particular bodices by high-bust measurement in certain circumstances because it can preserve shoulder and upper-chest fit before a bust adjustment is made.
This is one reason brand-specific instructions matter. A rule that is sensible for one block is not automatically correct for every pattern.
How do I size up or resize a sewing pattern?
If the size you need is already included in a nested multi-size pattern, use the correct size line or blend between the supplied lines. That is much safer than trying to enlarge or shrink the whole pattern with a photocopier.
Uniformly scaling a pattern changes every dimension by the same percentage. Real grading does not always work that way: widths, lengths, positions and circumferences need controlled changes. Simply enlarging the whole pattern can shift necklines, armholes, lengths and other details more than you intended.
If you need to move beyond the supplied size range, use a recognised grading or pattern-alteration method and check the result carefully. For a fitted or expensive project, make a toile or test garment before cutting your final fabric.
A simple size-selection process
- Take your current body measurements.
- Read the pattern company's size chart — ignore your ready-to-wear label.
- Identify the controlling measurement for the garment.
- Check the finished garment measurements.
- Work out the approximate ease at the key points.
- Decide whether the intended fit matches what you want.
- If you fall between sizes, plan where to blend between them.
- For an unfamiliar brand or close-fitting style, make a test garment where practical.
Frequently asked questions
How do I determine my size for a sewing pattern?
Take your current body measurements and compare them with the specific pattern company’s chart. Start with the measurement that controls the fit of that garment, then check finished garment measurements and ease.
Why is my sewing pattern size different from my shop size?
Pattern companies use their own sizing systems, and sewing sizes do not reliably correspond with ready-to-wear labels. Use the measurements printed for the pattern rather than the size number you normally buy.
What should I do if I am between sewing pattern sizes?
You can often blend or grade between the nested size lines, choosing the best starting size at the area that is hardest to alter and transitioning smoothly to another size at the waist or hip.
Can I simply enlarge a sewing pattern to size it up?
Uniformly scaling a pattern can change lengths, widths and positions in ways that do not match body growth. If you need a size outside the supplied range, use a considered grading or alteration method rather than simply enlarging the whole page.
How much bigger should a garment be than my measurements?
That depends on wearing ease, design ease, fabric stretch and the intended silhouette. Compare the finished garment measurement with your body measurement rather than relying on a universal allowance.
Useful references
For further reading, see the Sewing & Craft Alliance guide to taking body measurements, Simplicity measurement guide and Cashmerette's fit checklist.
Go deeper on sizing and fit
Understand Pattern Ease
Wearing ease, design ease, negative ease and a simple calculation.
Read the ease guide →Finished Garment Measurements
Use finished measurements to understand how the sewn garment will really fit.
Understand the measurements →Grade Between Sizes
Blend size lines without distorting the design or changing areas that already fit.
Learn how to grade →Before you buy or print the pattern
Once you have chosen the most sensible starting size, use my full pattern checklist to review the fabric, print scale, markings, grading and construction information.
Open the Pattern Checklist