Module 1 explained why sizes do not agree between brands, and Module 4 showed how to grade a pattern. This lesson looks at sizing from the maker’s side: how a label builds its own size chart, chooses a fit model, decides a size range, and keeps fit consistent. It is the knowledge every ready-to-wear trouser maker needs.

Three trouser fronts nested, small, base and large, graded from one base size on the Part IV women’s front block, with arrows showing the grade at the waist, hip and rise and the note that rise and crotch grade less than waist and hip
Nested grade: waist and hip move more than rise and crotch.

What you’ll learn

  • How a brand builds its own size chart.
  • What a fit model is, and how small labels work without one.
  • How to choose a size range, including extended sizes.
  • How fit stays consistent across sizes and seasons.

Building a size chart

  1. Know your customers: who they are, their ages, where they live. A college label and a label for older women need different charts.
  2. Collect measurements: from your own made-to-measure records (with permission and without names), from published data, and from any national survey results (see Size systems and the India size survey in Module 1).
  3. Choose a base size near the middle of your customers.
  4. Set the steps between sizes (the grade): usually larger for waist and hip, smaller for rise and length.
  5. Decide the size names: numbers (28, 30, 32), letters (S, M, L), or UK-style numbers, and show the body measurements for each.
  6. Test it: make samples in several sizes and try them on real people at each size.
  7. Publish it with body measurements and garment measurements, in inches and cm.

Fit models

A fit model is a person whose body is the reference for a brand’s samples, usually in the base size. Samples are tried on them, and the pattern changed until it fits. Because one body cannot represent a whole range, larger brands may use fit models in several sizes.

  • Small labels often use the designer, a staff member or a trusted, regular volunteer. This is normal. What matters is that the same person is used across a season and that their measurements are written down.
  • A dress form padded to the fit model’s measurements helps between fittings (see Draping basics: the form, padding and grain in Module 5).
  • Fit models are working people: pay them fairly, agree hours, and respect privacy and consent, especially for photos.
  • Children: children’s fit sessions are short, with a parent present, with consent, and over underclothes.

Choosing a size range

  • Start smaller than you hope to end: three to five sizes is common for a new label.
  • Extended sizes (plus and petite) need their own fit checks. Bodies do not simply scale up; seat shape, tummy and thigh change in different ways (see Module 3).
  • Length options: short, regular and long inside legs, or an unhemmed option for alteration.
  • Children: size by height and age together, with growth room (see Children’s sizes by age and height, and ease for every style in Module 4).
In more depth: why grading rise and crotch is hard

When a trouser is graded up, the waist and hip grow by a set amount per size. The rise and crotch curve should grow much less, because people of larger sizes are not proportionally taller. A simple grade that adds the same proportion everywhere gives larger sizes a rise that is too deep and a crotch that hangs. That is why the size set must be checked on bodies, and why experienced pattern makers check rise and crotch first on any grading spec. See Grading across sizes and Grading children’s sizes and checking a graded set in Module 4.

In more depth: vanity sizing and labels

Over decades, many brands have put smaller size numbers on larger garments, so that a size label today may be bigger than the same label years ago. This is called vanity sizing. For your own label, the honest course is to publish body measurements with each size, so the label number matters less than the numbers in the chart.

In more depth: standards you may meet

International and national standards set ways to define body measurements and to show sizes on labels: ISO 8559 (international), EN 13402 (Europe), ASTM body measurement tables (United States), and standards from the Bureau of Indian Standards (BIS). They are usually voluntary unless a law or a buyer requires them. Export buyers often supply their own charts. Check the current edition on the standards body’s website before relying on one.

Tips, tricks and hacks
  1. Write down the fit model’s measurements at every fitting season; bodies change.
  2. Use the same person for all fittings of one style.
  3. Try samples on two or three extra bodies at the edges of your range.
  4. Publish garment measurements as well as body measurements.
  5. Keep a size-chart version number and date.
  6. Record returns by size to spot a size that does not fit.
  7. Offer unhemmed lengths or free hemming to cover leg-length differences.
  8. Grade rise gently; check it in the size set.
  9. Use photos of the fit model (with consent) to compare seasons.
  10. What professionals do differently: they treat the size chart as a product, reviewed every season.
Problems and how to fix them

The largest size fits badly at the seat

  1. Fit the largest size on a real body and correct the pattern.
  2. Change the grade for that size, not only the base.
  3. Prevention: check the size set on bodies, not just with a tape.

Customers say “I’m usually a 32 but your 32 is tight”

  1. Check your 32 against your published chart.
  2. Show body measurements more clearly.
  3. Prevention: publish measurements, not just size numbers.

Fit changes from season to season

  1. Compare with the last season’s sealed sample.
  2. Check the fit model’s measurements.
  3. Prevention: keep base patterns under version control and use one fit model.

The rise is too long in large sizes

  1. Reduce the rise grade.
  2. Redraw the crotch curve for those sizes.
  3. Prevention: grade rise less than hip.

Petite customers find every trouser too long in the rise

  1. Offer a petite fit with a shorter rise and inside leg.
  2. Offer alteration.
  3. Prevention: test samples on shorter bodies.

Children outgrow sizes too fast

  1. Add growth tucks or adjustable waists.
  2. Size by height, not age only.
  3. Prevention: build growth room into the chart.

The fit model leaves mid-season

  1. Find someone with close measurements and pad a form to match the records.
  2. Fit the remaining styles on the padded form, then check on the new person.
  3. Prevention: keep full measurement records and photos.
Common misunderstandings
  • “There is one Indian size standard all brands use.” Brands mostly set their own charts; national survey results are still being taken up.
  • “Grading is just making everything bigger.” Different measurements grow by different amounts.
  • “Fit models must be professional models.” At small scale, any consistent, consenting person with recorded measurements can serve.
Check yourself
  • Can I explain how a brand builds its size chart?
  • Do I know what a fit model is and how to work with one fairly?
  • Do I check rise and crotch across the size set?
  • Do I publish body and garment measurements?
  • Do I treat children’s fit sessions with extra care?
Key terms
  • Base size: the size the pattern is first made and fitted in.
  • Grade rule: the change in each measurement between sizes.
  • Fit model: the person whose body is the reference for samples.
  • Vanity sizing: labelling garments with smaller size numbers than their measurements suggest.
  • Extended sizes: sizes outside a brand’s usual range, such as plus and petite.
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