You've found a Lacoste polo you like, the listing says "FR4" or just "Size 4", and now you're trying to work out whether it'll actually fit. It's the question we get asked more than any other, so here's the straight answer.
The short version: FR2 is an XS, FR3 a Small, FR4 a Medium, FR5 a Large, FR6 an XL, FR7 an XXL. That'll get you in the right ballpark. The longer version matters too, because Lacoste runs slim and the number on the label isn't the whole story.
So what does "FR" actually mean?
Nothing exotic — FR is just France. It's the French numeric system Lacoste uses instead of S/M/L, so "FR4" and "Size 4" are the same thing. The numbers climb from about 2 at the small end upward.
The conversion (men's polos)
This follows Lacoste's own guide for classic-fit men's polos:
| Lacoste (FR) | UK / Alpha | Approx. chest |
|---|---|---|
| FR2 | XS | ~38" / 98cm |
| FR3 | S | ~40" / 103cm |
| FR4 | M | ~42" / 108cm |
| FR5 | L | ~45" / 115cm |
| FR6 | XL | ~48" / 122cm |
| FR7 | XXL | ~50" / 129cm |
So an FR4 lands around a UK Medium and an FR5 around a Large.
Why the chart only gets you halfway
Two things trip people up. First, Lacoste is cut slim for UK tastes — if you like a bit of room, or you're hovering between sizes, go up one. Plenty of solid UK Mediums are happier in an FR5. Second, the numbers don't behave identically across every fit and era. Slim-fit, classic-fit and older vintage pieces all wear differently, and vintage Lacoste in particular can stray a fair way from the modern chart.
Which is why, honestly, I trust the tape measure over the label every time.
How to measure one properly
Here's exactly what we do before a piece goes up for sale, and what I'd suggest you do with anything you already own:
Lay the polo flat and buttoned, front up. Measure straight across from one armpit seam to the other — that's the pit-to-pit. Double it and you've got the full chest. Now compare that against a polo of yours that fits the way you like. That comparison tells you more than any size label, especially on pre-loved or vintage gear where the tag might have faded or the sizing's drifted over the years.
Jackets and knitwear
The chart above is polo-specific. Jackets, sweats and knits use the same FR numbers but with more room built in, so an FR4 jacket sits looser than an FR4 polo. Same advice — go by the listed chest measurement, not the number.
FAQs
What's FR4 in UK size? Roughly a Medium, around a 42" chest. Bear the slim fit in mind.
Is FR5 a Large? Yes, broadly — about a 45" chest.
Is "FR4" the same as "Size 4"? Identical. Just the French numeric size.
Why does mine feel small for the size? Lacoste fits slim by UK standards, and fit varies by style and era. Size up if in doubt, or go off the pit-to-pit.
Finding your fit with us
Every Lacoste piece we list has its actual garment measurements on the page, so you're buying to a real chest figure rather than guessing off a label. Have a look at the current Lacoste collection.
Want to be sure yours is the real thing as well? Here's our Lacoste Authentication Guide.
