Body measurements vs garment measurements

A body measurement is taken on the person: around the chest under the arms, around the natural waist, around the fullest part of the hips. A garment measurement is taken on the product, usually laid flat on a table and measured edge to edge. A body chart says "if you measure this, take this size". A garment chart says "this is how big the shirt is".

The two numbers are never equal for the same size, and they shouldn't be. A shirt has to be bigger than the body inside it. When a shopper compares their own chest with a garment number, they pick a size that is too small, or decide nothing fits.

Two charts for the same shirt

Ruban Size's men's T-shirts template gives both, in two tabs. Here are the chest rows side by side, with the flat value doubled into a circumference:

The M shirt measures 106 cm around. The body it is meant for measures 96 to 103 cm. The 3 to 10 cm of difference is ease: the room that lets you move, sit and breathe. How much ease clothes need gives the numbers by garment.

Read the table the wrong way and things go wrong fast. A shopper with a 96 cm chest who sees "53" thinks every size is far too small. A shopper with a 104 cm chest who reads the 106 cm M as "just big enough" gets a shirt made for a 96 to 103 cm chest: one size too small.

Flat vs around

Garment measurements come in two forms, and the header should say which:

• Laid flat (also "half chest", "width", "pit to pit"): the garment lies on a table and you measure across the front, from one side seam to the other just under the arms. You get half the circumference. Double it to compare with anything taken around.
• Around: the full circumference of the garment, like a tape around the body. Some charts give the waistband of pants this way.

Lengths are different again. A body length, a sleeve or an inseam measured on the garment is a straight line, not a circumference: it is never doubled. How to measure a garment flat shows where to put the tape for each one.

Which one should a store publish?

Body measurements are the easiest for shoppers: they measure themselves and read the size. The brand's own ease is already built into the ranges, so nobody has to know what ease is.

Garment measurements describe the product honestly. They suit shoppers who lay a favorite shirt on a table and compare, and they are the only option when a piece is one of a kind and no body range was ever made for it.

The best charts give both, in separate tabs, with clear headers. That is how the templates do it:

• Women's tops: Body measurements (chest, waist, hips), then Garment measurements, laid flat (length, sleeve).
• Men's T-shirts: Body measurements (chest, waist), then Garment measurements, laid flat (length, half chest).
• Coats and jackets: Body measurements, then Garment measurements (back length, sleeve length).
• Men's big and tall: Body measurements, then Garment measurements (body length, sleeve length).

In these templates, Find my size works from the body tab, and the garment tab answers the shopper who wants to know how long the sleeve is. Try both tabs here:

How Ruban Size reads a garment chart

Find my size always asks shoppers for body measurements, because that is what a person can measure. When the chart holds garment measurements instead, it converts before comparing:

1. It detects them. Headers with words like flat, laid, half, width, pit to pit, garment or product (and their French, German, Spanish and Italian words) mark a garment row. So do values too small to be a body: an adult chest or bust under 72 cm, a waist under 52, hips under 68, an underbust under 55. Those are read as half circumferences.
2. It doubles flat values. A laid-flat 53 becomes 106 cm around.
3. It adds ease for the garment type and for the fit the shopper picks under "Fit I like" (Snug, Regular, Loose). Jersey and stretch fabrics take a little off.
4. It says so. The answer carries the line "This chart gives the garment's own measurements: we added room for the fit you chose."

A worked example

A shirt chart has a single row, "Half chest, laid flat (cm)": 50, 53, 56, 59 and 62 for S to XXL. A shopper enters a 96 cm chest.

The M shirt is 106 cm around, so a regular fit lands on M, and a shopper who likes room gets the 112 cm L. A plain lookup would compare 96 with 50 and say nothing fits, or compare it with the doubled 100 and give an S that sits tight.

That difference shows in Ruban Size's benchmark of 40,000 simulated shoppers drawn from NHANES 2015 to 2018 and ANSUR II: on garment-measurement charts, Find my size gave the exact size 64.5% of the time, against 9 to 14% for a plain lookup in the chart.

When the header doesn't say

Full garment circumferences labeled only "Chest" look exactly like body measurements, and no detection can tell them apart. Say it in the editor instead: in the Fit and Find my size tab, set Measurements in the table to Garment measurements. Room added to garment measurements lets you replace the usual room for the garment type with your own, for a regular fit.

All of this is in every plan, on charts you build in the size chart editor or start from a template like coats and jackets. More on the answer itself on the Find my size page.

Questions

What does "pit to pit" mean on a size chart?

It is the width of a garment laid flat, from the seam under one arm to the seam under the other. It is half the chest circumference: double it before comparing with your chest, and expect the garment to be bigger than you.

Should a garment measure the same as my body?

No. A woven top that measured the same as your chest would be skin tight. The difference is ease, from about 9 cm at the chest for a fitted top to more than 15 cm for a coat.

How can I tell if a size chart shows body or garment measurements?

Read the header first: words like garment, product, flat or half mean the product. Then read the numbers: an adult chest in the 40s or 50s of centimeters is a laid-flat value, and single values per size (rather than ranges) usually come from measuring a garment.

Can a size finder work from garment measurements?

Yes, if it adds ease. Ruban Size's Find my size detects garment rows, doubles flat values and adds room for the garment type and the shopper's preferred fit before it compares.