This question on jacket length comes from our online community:
"What's the difference between a 40R and 40S?"
Regular vs short jacket - which to choose, how much of a difference is there, and how to measure?
This brief guide will offer some historical context, show you how to properly measure a jacket's length, and offer a visual representation of the difference in length between a Regular and Short suit jacket.

Jacket Length Evolution:
Historically, the length of the jacket runs parallel to the cycles of fullness or trimness of suit cut.
The 1940s saw fuller-cut menswear. The trousers were worn at the natural waist or higher and the jacket shoulders were significantly built up to present a powerful silhouette. Also, in many cases, the jacket hem were quite long by today's standards, extending beyond the tip of the thumb.
Smile Standing Sleeve Gesture Tie
Trousers Suit trousers Suit Blazer Smile
Men's Jackets were longer in the 1940s​
Ultra-long jackets of the 2003 NBA Draft!​

This trend repeated itself, albeit to an extreme, in the late 1990s and early 2000s. Look no further than the NBA players above!
Conversely, the 'bum freezer' suits of the 1960s, popularized by the Beatles and British counterculture, saw a significantly trimmer silhouette. These featured slim trousers cropped around the ankle and jackets barely covering the seat-if at all.

Suit trousers Photograph Smile White Standing
Suit trousers Shirt Dress shirt Sleeve Gesture
1960's "Bum Freezer" suit​
Thom Browne's "shrunken" suit​

In the mid-to-late 2000s, the suit began to 'shrink' once more, mirroring the slimmer T-shirts and 'skinny' jeans dotting both the catwalk and the city crosswalk.

Somewhat infamously, designer Thom Browne debuted suits with severely cropped trousers and jacket hems sitting high on the hips- not even reaching the wristbone, much less the knuckles of the thumb.

The 2010s and into 2020 saw a gradual lengthening of the jacket to a more traditional position, with longer rear vents and the hem resting just below the seat.

So, how should one measure a jacket?

Regular vs Short Jacket Length: Measured
To measure the rear length of a jacket, flip up the collar and run your tape measure down the center seam from the crease in the collar to the bottom of the hem.

This works best if the jacket is on a sturdy wooden hanger. But, it can also be done on any flat surface.

Outerwear Shoulder Product Overcoat Coat
Outerwear Neck Textile Sleeve Dress shirt
38S Suit Jacket​
38R Suit Jacket​

The jacket on the left (38S) shows that it is approximately 1.5in shorter than the jacket on the right (38R).
It's important to note, however, that Regular and Short Jackets can vary by brand. What one brand calls a 'Regular' may not be the same as another. The 38S on the left is from SuitSupply, and the 38R on the right is from Spier & Mackay.

Speaking broadly, however, a brand's Short jackets will be between 1.5 and 2 inches shorter than a Regular. A 'Long' jacket, then will sit 1.5 to 2 inches longer than a regular jacket.

Now, let's take a look at how a Regular and Short jacket look on a model.

Off-the-Rack Regular vs Short Jacket Length: A Visual Comparison
The jacket on the top is an off-the-rack 38S. The Jacket on the bottom is an off-the-rack 38R. The Model stands 5'7.25", or just over 170cm.

Footwear Dress shirt Neck Sleeve Grey
Leg Waist Sleeve Dress shirt Knee
Joint Trousers Shoulder Leg Neck
38S Front View​
38S Rear View​
38S Side View​

Footwear Trousers Dress shirt Fashion Neck
Joint Leg Textile Sleeve Waist
Joint Trousers Leg Human body Sleeve
38R Front View​
38R Rear View​
38R Side View​

Which is the correct choice? As we have established, historical context is key. Neither the jacket on the left nor the right is 'incorrect.'
However, the 38S jacket would be the better choice, for this particular person, for two reasons:
  • From the front, the jacket cuts him, visually, in half, and elongates his shorter frame.
  • At the rear, the jacket covers the seat, but does not extend so far that it curves back in down the thighs.
These tips are more 'guidelines' than hard and fast rules.
A shorter man (under 5'8") may consider taking a slightly shorter hemmed jacket. This, along with a higher rise on the trouser, gives the illusion of longer legs and greater height.
A very tall man with longer legs and shorter torso may consider a slightly longer jacket to ensure his silhouette is nicely proportional.

A Note on the "Thumb test"
In some instances, men have used the 'thumb test' to determine correct jacket length. This method says the jacket hem should sit in the middle of the thumb, at the first knuckle from the tip.

Arm Dress shirt Neck Sleeve Gesture
Outerwear Dress shirt Sleeve Gesture Grey
38S close up​
38R close up​

However, some men have much longer arms than others. Strictly following this rule may result in a very long jacket! So, we'd recommend using it sparingly, and in conjunction with the other two guidelines we recommend above.

Jacket Back
The jacket back should be long enough to cover the curve of your rear with ½ inch to spare.
Run a tape measure from the base of the collar to the bottom of the jacket in back. Then make sure that the measurement taken is the same for the measurement from the bottom of the back of the jacket to the floor.

Ask Andy Standard Rule
The AskAndy Standard Rule is:
HeightJacket Length
Under 5'8"Short
5'8" to 6'0"Regular
6'1" to 6'4"Long

A Final Note
If you find a jacket at an excellent bargain that is slightly too long, it can be made shorter. But, this is a risky, expensive tailoring endeavour, and it may not always work out.
This is especially true if the hem of the jacket is curved. The 'balance' of the garment may be compromised if the hem is brought too close to the pockets.
You've got about an inch to work with, but we wouldn't suggest bringing it up any more than that.
Hopefully this guide has been helpful in visualizing your decision!

Regular vs Short Jacket Length Discussion
Please come join us in the Regular vs Short Jacket discussion in our online community!