A well-fitting shirt should look clean without feeling restrictive. That sounds simple, but labels such as regular, tailored and slim are not universal measurements. One brand’s tailored fit can be another brand’s regular fit, and the same size can sit very differently depending on the cut, fabric and intended style.
So, ignore the label for a moment. The most reliable way to judge a shirt is to look at how it sits on the key parts of your body. And to check it while moving and sitting, not only while standing in front of a mirror.
At Jack Martin, our rule is straightforward: not baggy, never tight, just tidy.
Start with the whole shirt, not one measurement
A shirt can have the correct collar size and still fit badly everywhere else. Equally, a shirt that looks sharp across the chest may become uncomfortable the moment you sit down. Before examining each area, button the shirt fully and try three simple movements:
· Sit down naturally and check whether the front buttons begin to pull.
· Reach both arms forwards as though holding a steering wheel.
· Raise your arms and check how much the shirt lifts out of the waistband.
A good fit allows normal movement without turning the shirt into a loose tent. Small creases are normal; strain lines, gaping buttons and large pools of excess fabric are not.
1. The collar: close, comfortable and clean
The collar should sit close to the neck when fully buttoned, but it should not feel like it is pressing into your throat. You should be able to slide one or two fingers between the collar and your neck without forcing them in. More space than that often makes the collar look oversized, particularly when worn with a tie.
Pay attention to how the collar behaves throughout the day. It should remain in place rather than lifting away from the neck, collapsing under a jacket or creating a visible gap at the back. If you wear a tie, button the collar and tie it properly before deciding whether the fit is right.
Too tight: pressure at the throat, visible pulling around the top button or discomfort when turning your head.
Too loose: a large gap around the neck, a collar that moves independently of the shirt or a tie knot that disappears into excess space.
2. The shoulders: the foundation of the fit
The shoulder seam should finish close to the natural end of your shoulder, where the shoulder begins to curve into the upper arm. It does not need to hit the exact millimetre, but it should not sit noticeably towards the neck or fall far down the arm.
Shoulder fit matters because it influences how the sleeves hang, how the chest moves and how the entire shirt looks under a jacket. It is also one of the more difficult areas to alter cleanly, so prioritise a good shoulder fit when choosing between sizes.
Too narrow: the seam sits towards the neck, the upper sleeve pulls and movement feels restricted.
Too wide: the seam drops onto the upper arm and the shirt looks slouched even when the rest of the body is not especially loose.
3. The chest: enough room to move, no button strain
Across the chest, the shirt should lie smoothly without stretching between the buttons. The clearest warning sign is an X-shaped strain pattern radiating from a button, or a gap that opens when you sit, reach forwards or take a deep breath.
Do not judge the chest only with your arms resting at your sides. Reach forwards and move naturally. A shirt is clothing, not a photograph; it must work when you do. At the same time, excessive fabric under the arms or broad folds across the chest usually mean the size or cut is too generous.
A small amount of ease is necessary, especially in woven dress shirts. Stretch fabric can provide additional comfort, but stretch should support the fit — it should not be used to hold together a shirt that is fundamentally too small.
4. The waist: follow the body, do not cling to it
A good shirt should follow the body, not cling to it. The waist can be shaped enough to avoid a boxy silhouette, but it should not pull across the stomach or create tension around the lower buttons.
This is where standing still can be misleading. A shirt may appear perfectly neat in the mirror but become too tight as soon as you sit down. Sit naturally, without holding your stomach in, and check that the button placket remains flat. If it bows or gaps, you need more room through the waist, either a larger size or a less tapered cut.
At the other extreme, too much fabric around the waist creates bulky folds when the shirt is tucked in. The aim is not to remove every crease. It is to keep the line clean while leaving enough room for comfort and movement.
5. The sleeves: finish at the wrist, not the hand
With your arms relaxed, the cuff should finish around the wrist bone close to the point where the wrist meets the hand. When worn with a jacket, roughly 1 to 1.5 cm of cuff showing is a useful guide, although personal preference and jacket sleeve length both matter.
The real test is movement. Extend your arms forwards. The cuff will move slightly up the wrist, but it should not retreat halfway along the forearm. A sleeve needs a little extra length to accommodate the bend of the elbow and the movement of the shoulder.
If the sleeve bunches heavily above the cuff when your arms are relaxed, it is likely too long. A small fold is normal and often necessary; a concertina of fabric is not.
6. The cuffs: secure without squeezing
A button cuff should sit securely around the wrist without rotating freely or sliding over the hand. You should still be able to move your wrist comfortably. If you regularly wear a watch, you may prefer slightly more room on that side.
Double cuffs are designed to have more presence. Once fastened with cufflinks, they should fold cleanly and remain close to the wrist without feeling tight. They should not flare open dramatically or disappear completely inside a jacket sleeve.
7. The shirt length: long enough for its purpose
Formal shirts intended to be tucked in should have enough length to stay inside the trousers during normal movement. If it repeatedly comes untucked when you reach or sit, the body may be too short, although very low-rise trousers can contribute to the problem.
Casual shirts designed to be worn untucked should be shorter and usually have a hem shaped for that purpose. As a general visual check, it should cover the waistband without hanging so low that it resembles a tunic. The correct length depends on your height and proportions, so the intended styling matters as much as the measurement.
The clearest signs that your shirt is too tight
· The buttons pull apart or form visible X-shaped strain lines.
· The collar presses into the neck when buttoned.
· The shoulder seams sit towards the neck and restrict arm movement.
· The fabric pulls strongly under the arms or across the upper back.
· The front placket bows or gaps when you sit down.
· The sleeves ride far up the forearm when you reach forwards.
The clearest signs that your shirt is too loose
· The shoulder seams fall noticeably onto the upper arms.
· The collar stands away from the neck.
· Large folds collect around the chest, back or waist.
· The cuffs slide over the hands or rotate constantly.
· The sleeves bunch heavily above the cuffs.
· Tucking the shirt in creates a large balloon of fabric around the waistband.
Regular, tailored or slim: which label should you choose?
Treat fit names as a starting point rather than a guarantee. Regular fit usually offers more room through the chest and waist. Tailored fit generally keeps comfortable chest room but removes more fabric at the waist. Slim fit is normally narrower throughout. The exact measurements, however, vary from brand to brand.
Choose the cut that gives you the cleanest line without creating tension. Sizing down simply to achieve a slimmer appearance often makes the shoulders, collar and chest too small. A better-shaped cut — or a made-to-measure shirt — is usually a better answer than forcing the wrong size.
How Jack Martin shirts are designed to fit
Jack Martin shirts are designed with a clean regular fit: enough room to move comfortably, without the oversized, boxy appearance sometimes associated with the word “regular”. The silhouette is tidy through the body while allowing the collar, chest and shoulders to do their job properly.
Our size labels are paired with collar-size guidance, and individual product pages provide the information you need to choose confidently. Fabric also affects the feel of a shirt, so a soft jersey, a crisp woven cotton and a cotton-stretch blend may sit differently even when the underlying pattern is similar.
When standard sizing is not quite right, customisation or made-to-measure can solve the problem more intelligently than repeatedly compromising between two sizes. Collar, cuff, sleeve and body proportions can be adjusted around the wearer rather than asking the wearer to adapt to the shirt.
A 30-second fit check
Before removing the tags, button the shirt fully and ask:
· Can I button the collar comfortably and turn my head?
· Do the shoulder seams sit close to the ends of my shoulders?
· Can I sit and reach forwards without the buttons pulling?
· Does the waist follow my shape without clinging?
· Do the cuffs finish at the wrist and remain there during movement?
· Does the shirt stay tucked in, or sit at the right length when worn out?
If the answer is yes throughout, the fit is probably right. It does not need to look vacuum-sealed or completely crease-free. It simply needs to look considered, feel comfortable and remain balanced when you move.
Not baggy. Never tight. Just tidy.
Find your fit
Explore Jack Martin shirts and use our size guidance to find the cleanest fit for you. When standard proportions are not quite right, our customisation or made-to-measure shirts allow the shirt to be adjusted around the wearer, not the other way round.
