Clothing Size Conversion: Why a Size Chart Is Not a Spec

A size chart is a set of measurements, not a set of labels. Converting one market’s chart for another means rebuilding those measurements, and it cannot be done letter to letter: the same letter sits at a different point on a different body, and only the numbers say which body you cut for. This page covers what changes between two charts and what has to be written down.

Why is a size chart not a spec?

Every label is a pointer to a row of measurements, and that row is the product: chest, waist, hip and sleeve, each with a number and a tolerance. A chart that lists only letters has kept the pointer and dropped the row, so a conversion built on it can only shuffle pointers.

The route that works runs label, then measurements, then label. Read what the first chart says the garment measures, decide what the second market’s body needs at that point, and write a new row. Conversion is not grading either: grading adds sizes along one axis, while conversion answers what a second market calls a garment that already exists. The circumference axis belongs to our plus size grading and fit page.

Why can two size charts disagree and both be right?

Two charts can describe the same garment, return different numbers, and both be right. Only three things can differ: whether the chart describes the body or the finished garment, how much ease the number holds, and how the tape was placed. Change one and a correct number stops matching another correct number.

A chart written on the body records what the wearer measures; a chart written on the garment records what the piece measures, ease included. Side by side, the gap is the ease, which nobody wrote down. Tape position cuts the same way: chest at the fullest point and chest below the armhole seam share one name.

This is why a chart has to travel as numbers, not as a link to a retail size guide, which is the rule our hoodie tech pack page sets out. It is also why we grade US, EU and Asian sets from the chart you send, as the yoga wear manufacturer page describes.

Variable	One chart says	The other says	Where a conversion breaks
What is measured	The wearer, bare skin	The finished piece	The same letter covers two bodies
Ease	Excluded from the number	Held inside the number	It arrives tight or oversized
Tape position	Chest at the fullest point	Chest below the armhole seam	A number nobody can reproduce
Wash state	The garment before the wash	The garment after the wash	Length moves after the first home wash
Size step	One even increment	A step that compresses at the top	Top sizes drift out of the run
Tolerance	Stated per point	Not stated	Nobody can accept or reject

What does a flat measurement tell you that a body measurement does not?

A garment laid flat and measured across the chest gives half a circumference. Double it and you have the garment’s circumference, not the wearer’s. The gap between that figure and the body measurement on the second chart is the ease.

Two details sit inside it. A knit is measured flat and relaxed or flat and stretched, and the readings are not interchangeable; on a 240–550 gsm fleece the two readings sit further apart than the tolerance you would set for that point. The tape has to be fixed too, edge to edge or seam to seam, or the two charts measure two spans.

What does 170/88A say that a letter size does not?

A numeric code of the 170/88A kind carries three facts in one label: a body height, a net circumference, and a body type category. None is a garment measurement. The code describes the person the garment is drafted for, and the factory still adds ease before a pattern exists.

The letter at the end is a proportion category, not a fit preference: it groups bodies of a similar build at that height, so it describes the frame rather than how loosely someone wears a hoodie. Height and length sit together in the same code, and the length axis is set out on our petite and tall grading page. Treat the code as a letter and shoulder width and body length are taken from the wrong run.

Which version of the garment does the chart describe?

A chart describes a garment at one point in its life, and the point that matters is after the wash. Bulk cloth is pre-shrunk before cutting, so the pattern carries one allowance for what the cloth does; a garment wash comes later, on the assembled piece, and moves size, hand and colour at once. The tape measure your customer owns meets the washed garment, not the one on the cutting table.

The end point of a conversion is a washed garment with a tolerance for each point, not a net body plus an ease factor. Write the chart on the unwashed sample and the first home wash becomes a second conversion.

Why does every point of measure need a tolerance?

A measurement without a tolerance cannot be accepted or rejected. The factory has to decide pass or fail at the cutting table, and the inspector again at final check: 100% inspection, accepted to AQL 2.5, still needs a range. Two garments cut from one pattern never measure identically, so the chart says how far each point may sit from the stated number.

Each tolerance belongs to one point and one method. A chest allowance and a sleeve allowance are not the same width, and a tolerance written for a flat measurement does not carry over to one taken on the body. Every style we cut carries an approved order file with the construction method for each part, the size chart and its tolerances, as our cutting and sewing page sets out. A chart without tolerances is an incomplete order file.

How is a chart converted without going label to label?

Work in four steps. Fix the base size and the row that belongs to it, with the method and the wash state. Convert each point on that row to the second market’s body, then convert the steps between sizes so the run keeps its shape at both ends. Re-label the row only once the numbers are settled, and mark every point the source chart left blank, so a blank stays a question.

What has to be in the chart before it can be graded?

Six things per row: the point, the tape position, whether the number is flat or on the body, whether the garment is washed, the measurement at the base size, and the tolerance. Add the base size and the run above it. The size range field of the knitwear tech pack template holds the run and the increment per point.

Such a chart can be quoted against. Rows missing come back as a list of questions, and every question stops the clock: the first sample takes 3–7 working days from confirmed design, so a chart that arrives a week late takes the sample with it.

Does a second size range make a second style?

No. A run of sizes for the same design is the same style, and sizes can be mixed inside one style and one colour, so 100 pcs per style, per colour holds, with 200 pcs on bonded or seam-sealed builds. We accept special measurements and unusual runs. Any detail that changes the set-up is confirmed when the quotation is drawn up, as the 100 piece order page sets out.

What should the RFQ say about the target market?

Name the market the chart is built for, the version of the chart you are sending, and whether its numbers are body or garment. Say whether the piece is washed before measuring, and give the run and the split. An RFQ that omits the market comes back priced on an assumption, as the RFQ fields page explains.

What do buyers ask most about clothing size conversion?

Can you convert a US size to an EU size for me?

Not as a letter: a letter is a position in one run, and that run is not the run you sell into. Send both charts, or send the measurements your market’s chart uses and say how the tape is placed. We rebuild the row and label it afterwards.

Why do I need to send a chart if I already gave the size range?

A size range names the sizes; it does not say what any of them measures. XS to 3XL as standard tells us where the run starts and ends, and nothing about the chest, the ease or the tape position. Send the chart, even a rough one, and the range becomes rows we can grade.

Do you measure the sample flat or on a body?

Both, and the chart has to say which one it uses. Production measures flat, because a garment on a table can be measured the same way twice. A body measurement is taken on a fit model during sampling and cannot be repeated at the end of the line. The chart that travels into bulk is the flat one.

What is the difference between a size chart and a size spec?

A chart is one row; a spec is the document around it. The spec carries the base size, the run, the method for each point, the wash state and a tolerance per row, and an approved order file is built from it. A chart without them is a list of numbers with nothing to check them against.

How long does a converted chart take before a sample?

The chart itself is settled in the quotation conversation, and sampling starts from confirmed design: 3–7 working days to the first sample. A chart that arrives after sampling has started does not slow the sample, it restarts the window. Bulk then runs 15–25 days after sample approval and deposit.

Can sizes be mixed inside one order?

Yes. Sizes can be mixed inside one style and one colour, so a run weighted towards the middle of the range is still one minimum: 100 pcs per style, per colour, with 200 pcs on bonded or seam-sealed builds. Colours do not mix, and a special measurement is agreed at quotation.

Send the chart your market uses, the run you intend to sell, and the market it is built for. We will name the missing rows before the quotation. First sample takes 3–7 working days; bulk runs 15–25 days after sample approval and deposit. The plants cover 18,000+ m² with 180+ staff across four lines, so the chart agreed at sampling is the chart the line cuts to.