Collar, cuff, and the torso of a dress shirt.

Button the collar and look across the table, which is how everyone else will see it. A gap at the neck and a cuff that vanishes under a jacket are the public fit. The private fit, the chest and the waist, is where most shirts fail, ballooning under the jacket or pulling open at the sternum. A tee that fits is not a pattern for this. It has no collar stand, no cuff, and no shirttail. Use it for weekends. Use a measuring tape for the dress shirt.

A dotted shirt under a navy jacket is the context: collar framed by a lapel, cuff near a watch. Get those points right before you care about the dot.

Neck and collar

Measure the neck where the collar will sit, snug, then add room for comfort. A practical test in a shirt you own is simpler. Button it. You should slide one finger, maybe two, between the collar and the neck. If two fingers swim, the collar is loose and the tie, if you wear one, will not sit. If one finger will not enter, or the collar bites when you turn your head, it is small. A collar that gaps into a diamond at the throat when buttoned is either too tight or cut with a stand that does not match your neck. Going up a neck size fixes tightness. It does not fix a badly cut stand. Try another maker before you settle for the diamond.

Button-down, point, and spread are use cases, not a ranking. A button-down stays put without a tie, under a knit, on a day with no jacket. A spread frames a tie knot and sits cleanly under a jacket lapel. A point collar sits between them and is the default if you sometimes wear a tie and sometimes do not. Choose by the week you have. A man who never wears a tie does not need a wide spread that collapses without a knot. A man who wears a tie daily will find a button-down's buttons fighting the knot.

Both collar points should sit at the same height. A twist is a construction fault. You can resew a loose button. You cannot resew a collar that gaps because the size is wrong.

The sleeve and the cuff

Measure from the center of the back of the neck, over the shoulder, to the wrist bone, with the elbow slightly bent. Makers include the yoke in the sleeve number. Measuring from the shoulder seam only will make a correct shirt look short.

Under a jacket, the cuff should show about a quarter inch to a half inch beyond the jacket sleeve. Less, and the shirt looks unfinished. More than half an inch, and either the shirt is long or the jacket sleeve is short. Check with the jacket you actually wear. A shirt measured bare, then worn under a jacket with a short sleeve, will show too much cuff no matter how correct the tape was. If you rarely wear a jacket, end the cuff at the wrist bone, not in the palm. You should be able to see the base of your thumb without the cuff covering it when your arm hangs.

A barrel cuff, the kind that closes with a button, is the daily choice. A French cuff needs a cufflink and a jacket, and it is a poor match if you roll your sleeves to work. Roll a barrel cuff once if you must, and only if the forearm is not tight. A cuff that will not close over the watch you wear is too narrow. Try it with the watch in the shop. The watch in a photograph is not evidence that your watch will fit.

Chest, waist, and length

The torso is the failure. A shirt that fits the neck and balloons at the waist looks sloppy under a jacket and worse without one. Button it and pinch the side seam at the waist. About an inch of cloth is ease. A handful means the waist is cut full for you, which a tailor can dart if the pockets and the pattern allow. No pinch, and pulling at the buttons, means there is no ease. A tailor cannot add chest. If the buttons pull across the chest, go up a size and plan to take in the waist, or find a different cut. Do not buy the pull because the collar happened to fit.

The shirttail should stay tucked when you sit and when you reach. If it comes out, the tail is short or the trouser rise is too low to hold it. Fix the rise and the tail together. The shoulder seam should meet the shoulder bone. A seam down the arm will show under a close jacket, and a yoke that wrinkles while you stand still is tight or twisted.

Point	A working fit	A fail
Collar	One finger of room, points even, no diamond gap	Too loose to hold a tie, or too tight to turn your head
Sleeve	Center-back to wrist bone, elbow soft	Measured from the shoulder only, then "too short"
Cuff show	A quarter to a half inch under your jacket	Covered completely, or a wide band of cuff
Waist	About an inch to pinch at the side	A balloon, or buttons that pull
Tail	Stays tucked when you sit and reach	Escapes because the tail or the rise is wrong

Cloth weight

Poplin in a lighter cloth breathes and wrinkles. Twill and oxford show the weave and stand up to a bag strap and a commute. Hold the shirting up to the light. If you can see your hand clearly, you will see an undershirt, and you should decide on that undershirt in the shop. A cloth that hides the hand will hide the undershirt and will feel warmer in a July meeting. Neither is more correct. The room and the season pick.

Cotton wrinkles and absorbs. A blend may hold a crease and feel less fresh by evening. Linen is a hot-weather cloth with wrinkles you either accept or skip. If you sweat through the back by noon, pack a second shirt. A heavier weave will hold the damp.

The plain crew in that photograph ends at the hip. It is a tee. Its fit, close through the chest and finished with a band, will mislead you if you copy it onto a dress shirt. The dress shirt needs a collar, a longer tail, and ease you can tuck. Enjoy the tee for what it is.

Buying a shirt you have not tried on

Start from a shirt you own that fits, not from a letter on a tag. Record the neck, the center-back sleeve, and the chest around the fullest part, plus the waist pinch you liked. Compare those figures to the garment measurements on the product page. Letter sizes are not stable across makers. A "large" that fit last year from one maker is a rumor about the next maker.

If the page lists only small, medium, and large, with no inches, you are guessing. Order from a maker whose measurements you have checked, or go into a shop. Buy one cloth before you repeat it in four colors.

Under a jacket, a billow at the waist still shows, and a tight chest pulls the tie off center. Try the shirt with the jacket. The jacket hides less than you hope.

Read the live return terms before you order: whether a washed shirt can go back, whether tags must remain, and how many days you have. A collar half an inch off is not a shirt to keep out of politeness. Ask if the page is vague.

• Measure neck with room for one finger, and sleeve from center back to the wrist bone.
• Choose button-down, point, or spread by whether you wear a tie.
• Show a short band of cuff under the jacket you actually own.
• Pinch about an inch at the waist. Do not buy a chest that pulls.
• Confirm the tail stays tucked when you sit.
• Ignore tee fit when you are buying a dress shirt.
• Compare inches on the product page, then read the live return terms.

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