Sizes, from the side that receives them
Suit sizes: the number, the letter and the drop
A men's suit size is three pieces of information wearing one label. A number, sometimes a letter, and an assumption you never see. Charts are easy to find and they mostly agree with each other in the abstract, which is misleading, because a size chart is not a fact about bodies. It is a claim about one manufacturer's block. The same chest measurement can arrive here quoted as a 40, a 50 and a 40R depending on which country and which brand the shop is reading from, and all three can be correct. So this page does two things: it gives you the conversion, and then it tells you where the conversion stops working, which is the part that matters if somebody else is paying for the garment.
The three parts of a suit size
| The number | The letter | The drop | |
|---|---|---|---|
| What it is | The chest, in inches on the US and UK systems. A 40 is a 40 inch chest, as the maker measures it. | The length class. S, R and L, short, regular and long, applied to the body of the jacket and the sleeve. | The assumed difference between the jacket chest and the trouser waist, conventionally 6 inches or about 15 cm. |
| How the Continental number relates | Roughly the inch number plus 10. A 40 is about a 50, a 42 about a 52. It is arithmetic, not a standard. | Usually replaced by a separate code, and the German system in particular encodes build into the number itself. | Same convention, expressed in centimetres, and just as invisible on the label. |
| Where it stops being reliable | Immediately across brands. Two makers can cut a 40 two inches apart and both are honest, because each is describing its own block. | At the extremes and on unusual proportions. A long body with short arms fits no length class properly. | On anybody whose real difference is not 6 inches, which is a very large number of people. |
| What goes wrong | A shop orders by label and the garment arrives cut to somebody else's idea of that label. | The jacket length is right and the sleeve is not, or the reverse, because one letter had to cover both. | The trousers are wrong while the jacket is right, and the customer concludes the whole suit is wrong. |
| What to do instead | Send the chest measurement. It is one number and it removes the ambiguity entirely. | Send the back length and the sleeve length separately. They are separate fields for a reason. | Send the trouser waist. Never let it be inferred from the jacket. |
The drop is the part almost nobody knows is there, and it is the reason a suit bought as a set so often fits in the jacket and not in the trouser. Nothing on the label tells you an assumption was made about your waist.
The terms behind the label
Conventions rather than standards. That distinction is the whole point of this page.
- Drop
- The difference between the jacket chest and the trouser waist that a maker assumes when selling a suit as a set. Conventionally 6 inches, roughly 15 cm. It is an average, and it is applied to everybody who buys that size. If your actual difference is 4 inches or 9, the set was never going to work on you, and no amount of choosing a different size fixes it because the assumption travels with every size.
- Length class
- The S, R or L. It adjusts the body length and the sleeve together, in fixed steps, from one length block. It works for most people and fails for anyone whose torso and arms disagree, which is why it is the first thing to abandon when a garment is being made rather than bought.
- Nominal versus finished
- A nominal size names the body it is meant to fit; a finished measurement is the garment laid flat. A jacket sold as a 40 does not measure 40 across the chest, it measures the body plus the ease the maker chose. Comparing a nominal size from one brand to a finished measurement from another is the most common way people conclude a size chart is wrong.
- Block
- The base pattern a maker grades every size from. Two makers with different blocks produce different garments at the same stated size, both correctly. This is not sloppiness and it is not a conspiracy against the shopper. It is what a house cut is.
- Vanity sizing
- Labelling a garment smaller than the body it fits. Real, common in retail, and the honest reason a chart from one shop will not predict another shop. It is worth naming because people usually assume they have measured wrongly when in fact two brands simply disagree.
- Konfektionsgröße
- The German ready-to-wear size, which encodes build rather than only chest, so that the same man has a different number depending on whether he is cut as a regular, a short or a stout. It is the system that departs furthest from simple inch arithmetic, and it has its own page here because a single row in a conversion table does not do it justice.
- Sizing versus measurement
- A size is a shorthand for a body a maker has assumed. A measurement is the body. Everything on this page exists because the first is convenient and the second is true, and the gap between them is where garments go wrong.
Questions the chart does not answer
What size suit am I?
Measure your chest at the fullest point, keeping the tape flat and level, and that number is your size on the US and UK systems. Add roughly 10 for the Continental equivalent, so a 40 is about a 50. Then treat that as a starting point rather than an answer, because two makers can both cut an honest 40 two inches apart. If a shop has a chart, use that shop's chart, not a general one.
How do US and European suit sizes convert?
The Continental number is approximately the inch number plus 10. A 38 is a 48, a 40 a 50, a 42 a 52, and so on up. It is arithmetic rather than a standard, which is why conversion tables from different sources agree in the middle and drift at the ends. The German system is the exception worth knowing about, because it encodes build as well as chest, and we have written that one up separately.
What do S, R and L mean?
Short, regular and long. The letter adjusts the jacket body and the sleeve together in fixed steps. It is a reasonable compromise for a garment on a shelf and a poor one for a garment being made, because a long torso with short arms gets the wrong answer whichever letter it picks. When something is being made for you, the body length and the sleeve length are two separate numbers and should be sent as two separate numbers.
Why does my jacket fit but not my trousers?
Because of the drop, an assumption you were never shown. A suit sold as a set assumes a fixed difference between chest and waist, conventionally 6 inches or about 15 cm. If your real difference is smaller or larger, the trouser was wrong before you tried it on, and picking a different jacket size will not help, because the same assumption is applied at every size. This is the single most common fit complaint about ready-to-wear suits and it is structural rather than bad luck.
Can I order made to measure using my size?
Please do not, and this is the one place where we would rather refuse the shorthand. A label tells us which shelf you buy from, not how you are built. It carries nothing about your shoulder, nothing about how you are proportioned front to back, and nothing about the two fields most likely to end in a remake. Our own form carries 47 measurement fields of which 31 are required, and it is that long precisely because a size cannot stand in for any of them.
I am between sizes. Should I size up?
Not by default, and the usual advice to do so is worse than it sounds. Sizing up in a jacket moves the shoulder, which is the one thing an alterations tailor cannot fix without rebuilding the garment. Sizing down and letting out is often the better bet, since chest and waist have seam allowance and shoulders do not. If the garment is being made rather than bought, the question does not arise, which is rather the point.
Why do size charts disagree with each other?
Because each one is describing its own block, and a block is a house's idea of a body. Add vanity sizing in retail, add the difference between nominal and finished measurements, and two perfectly accurate charts will send you to different numbers. Nobody is lying. The mistake is treating any chart as universal, ours included. Check the chest measurement in centimetres and ignore the label.
What should a shop send us instead of a size?
Chest, waist and trouser waist at minimum, in centimetres, taken on the body rather than over a coat, plus a note on posture. That is more useful than any label from any market, and it removes the entire class of problem this page describes. If all you have is a size, say which country and which brand it came from, because that at least tells us which block somebody was reading.
Send the measurement, keep the chart for the shop floor
A size chart is a good tool for narrowing down a garment on a rail. It is the wrong tool for commissioning one. If you are ordering for a customer, send us the body.