Do Ariat M4 Jeans Run Big? The Same Pair in Two Sizes, Measured at 6’8″

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I am 6′8″. I had been wearing the Ariat M4 Low Rise Stretch Legacy Boot Cut in 40 x 36 all year and the waist always felt a shade generous, so I bought the same jean in 38 x 34 to find out what one size step actually buys you. Then I put a tape on both pairs, in the same places, on the same afternoon.

The short answer

The waist runs big and the leg runs short. Dropping from 40 x 36 to 38 x 34 took two and a half inches off the waist flat — five inches around, for a labelled step of two — and took two and a half inches off the inseam. The thigh did not change at all. Thirteen inches flat on both pairs.

So if the question is do Ariat M4 jeans run big, the honest answer is: in the waist, yes, and more than the label admits. In the leg they run short, and they get shorter the further down you go.

Both pairs, measured by hand

Every figure below came off my own tape. Nothing here is from a size chart. All measurements are flat unless stated, which means you double them to get the body measurement.

Measured flat	40 x 36	38 x 34	Change
Waistband	21.5″	19″	−2.5″
Front rise	12.25″	12″	−0.25″
Rear rise	17.25″	16″	−1.25″
Thigh	13″	13″	no change
Inseam	35.5″	33″	−2.5″
Leg opening	9.75″	9.5″	−0.25″

The thigh did not move at all

This is the finding I did not expect, and it is the one worth carrying into a different brand’s listing. Thirteen inches flat on both pairs. I dropped two full inches of labelled waist and the leg is identical.

What that means in practice: if an M4 is tight through the thigh, sizing up will not fix it. You will get a looser waist and a longer leg and the same thigh. If it is loose through the thigh, sizing down will not take it in. On this jean the thigh is a fixed cost, so it has to be right at whatever size you order — and on the 38 x 34 it sits tighter on me simply because there is less waist above it holding the jean up, not because the leg got narrower.

That is also the reason a second pair in another size is an expensive way to solve a thigh problem. It is the one dimension the size run does not give you.

The waist drops further than the label promises

The label says two inches. The tape says two and a half flat, which is five inches around. If you size down on this jean expecting the two inches you were sold, you will get appreciably more than you asked for.

In my case that was the point — the 40 was loose and the 38 fits properly. But it is worth knowing before you order, because a five-inch change around the waist is the difference between a belt and no belt, and it is not what a two-inch step implies.

Worth noting too: at 21.5″ flat the 40 measures 43″ around against a labelled 40. The vanity sizing is real and it is in your favour only if you know it is there.

The inseam runs short at both sizes, and it gets worse

A stated 36 taped at 35.5. A stated 34 taped at 33. Half an inch short, then a full inch short.

Half an inch on its own is nothing. The problem is the direction: the shortfall doubles as you go down the size run, so the shorter the leg you order, the less of it you actually get. On a 6′8″ frame there is no margin to give away, and a 33″ taped inseam on a boot cut is right at the edge of what clears a boot.

If you are relying on a 36 to be a 36, order the 36 and expect 35.5. If you are ordering a 34, expect 33.

About the “low rise” in the name

It is not low. The front rise taped 12.25″ on the 40 and 12″ on the 38, which sits mid-range for the jeans I have measured, not low. A reviewer disputing the low-rise claim on the listing is closer to right than the listing is.

That is good news if you carry anything in front, which is the usual reason a tall guy’s jeans slide down at the back — a 12″ front rise with a 16″ rear rise has enough height to sit where you put it. I wrote up how rise behaves across brands in the rise guide, and the short version is that you cannot compare rise between brands using the label size.

Where each number comes from

So you can repeat any of this on a pair you already own, or check a brand’s chart against your own tape.

Which one I would buy

The 38 x 34, which surprised me. The waist fits properly instead of nearly, the thigh is tighter but not uncomfortably so, and on a boot cut a little more leg tension arguably suits the shape. The 40 x 36 is the pair I have actually worn all year and it is a good jean — it is just a size too generous through the waist for me.

The honest catch, and the reason I am not calling the 38 a final keep yet: it is 99% cotton with 1% elastane, 12.75 oz ring-spun denim. That is the shrink-prone end of the fabric range, and at a taped 33″ inseam I have no inches to lose. The 36 has half an inch of margin. The 34 has none. I will update this once they have been through a few washes.

Both sizes, if you want them. The 40 x 36 and the 38 x 34 are separate listings on Amazon, not two options inside one. Measurements for both are in the table above.

What to do with this if you are tall

• Buy the waist you want, not the waist on the label. A labelled 40 measures 43 around here. Size by the tape.
• Add an inch to the inseam you need. Stated length runs short on both sizes I checked, and the gap widens as you go down.
• Sort the thigh first. The size run will not change it. If 13″ flat is wrong for you, this is the wrong model, not the wrong size.
• Ignore “low rise” in the name. It taped 12–12.25″ at the front, which is mid-range.

Every figure on this page is in the sizing database alongside the rest of what I have measured, and the jeans I compared these against are in six pairs of tall jeans, measured. Anything currently worth buying is on the deals page.

Tell me what to measure next

If you want a particular brand or model put on a tape, say so and I will add it to the list. Everything here is measured at 6′8″, by hand, on garments I bought.