How should a flat cap fit? Snug the whole way around the inner band, level on your head, with the brim about a finger's width above your eyebrows and no gap behind your ears. A flat cap carries no rigid leather sweatband the way a felt hat does, so the cloth sweat strip and the soft crown decide the fit together, and a cap one size off tells on itself immediately: it either perches on top of your head or swallows your ears. Since 1911, JJ Hat Center has been fitting caps in New York, and the four checks below are the ones we run at the counter before any cap leaves the store.
How Should a Flat Cap Fit? Four Checks in the Mirror
Put the cap on, pull it down until the band seats itself, and work through all four. They take a minute and catch nearly every sizing error.
- Even contact. Slide a fingertip around the inside edge, where the cloth sweat strip runs. It should press lightly and equally at the forehead, the sides, and the back. Firm at the front and loose at the back usually means a shape mismatch rather than a size error — a long oval head in a cap cut round — and the fix is a different pattern, not a different size.
- Brim height. The brim (the peak, in British usage) should cross your forehead a finger's width above the eyebrows, and the band should cover the tops of your ears. A brim that rides high on the forehead, leaving the cap balanced on the crown of your skull, is the clearest sign of a cap that is too small.
- The back edge. The back of the cap should come down over the curve of your skull and stay there. If it creeps up and shows skin above your ears at the sides, size up.
- Movement and marks. Turn your head left and right, look at the floor, walk a few steps. A cap that fits moves with you. Then wear it fifteen minutes, take it off, and check your forehead: clean skin means the size is right, a red line means it is a size too small. Cloth caps do not break in out of a size.
All four checks test size, not styling. How far forward you wear the brim and whether the crown leans left or right is a separate decision, and our guide to how to wear a flat cap covers it. Get the size right first; the styling only works on top of a cap that sits where it should.
Should a Flat Cap Be Tight or Loose?
Snug, and closer to the tight end than most people expect. The working test: you should be able to work a fingertip between the band and your temple against mild resistance, and the cap should not shift when you shake your head once, briskly. Anything you can rotate with a fingertip is too loose.
A cap that is genuinely too tight does more than ache above the ears. The shell is being pulled sideways, so the crown lifts into a dome instead of lying flat over the brim, the side seams take a strain they were not cut for, and the sweat strip rolls under the band where it rubs. None of that settles down with wear.
Too loose fails differently. The cap rides up rather than down, the crown balloons, the brim tips toward the sky, and the whole thing rotates a few degrees every time you turn a corner. On a windy avenue it will leave your head. A loose cap also reads wrong: the flat cap silhouette depends on the crown lying close, and surplus circumference reads as costume.
One honest allowance: a wool cap relaxes a little with body heat over a season of regular wear — roughly an eighth of an inch at the band, not a full size. Buy the cap that fits today, not the one you hope will come to you by March.
How Do I Measure My Head for a Flat Cap?
Use a flexible tailor's tape and run it where the band will actually sit: about an eighth of an inch above your ears, across the middle of your forehead, and around the bony ridge at the back of your skull. Keep the tape level the whole way around — a tape that slides down at the back reads short and sends you a size too small.
Pull it snug, the way a band rests, not tight the way a belt does. Measure three times and keep the largest reading, because heads are not perfectly round and the cap has to clear the widest path. Wear your hair as you normally wear it; at the top of a letter size, a quarter inch of volume is the difference between Large and X-Large.
No tape at home? Run a shoelace or a strip of ribbon around the same path, pinch where the ends meet, and lay it flat against a ruler. Work in inches first — US sizes are built from inches — and note the centimeter figure too, because most European cap makers print only that.
One judgment a cap buyer needs that a hat buyer rarely does: the front-to-back depth of your head, assessed by eye in the mirror. If your skull is noticeably longer than it is wide, caps cut on a round block will gap at the back at every size. That calls for a deeper pattern — a newsboy, or a cap with a generous back panel — not for going up an inch in circumference.
Flat Cap Sizes: Letters, Numbers, and Centimeters
A numbered hat size is the circumference of your head in inches divided by pi, roughly three and one seventh, which is why the numbers climb in eighths. Caps, though, are usually sold in letters, and the letters are a studio decision rather than arithmetic. Use the table to translate between all three before you order.
| Letter size | Head circumference (inches) | Numbered size | Centimeters |
|---|---|---|---|
| Small | twenty-one and five-eighths to twenty-two and three-eighths | 6 7/8 to 7 1/8 | fifty-five to fifty-seven |
| Medium | twenty-two and three-quarters to twenty-three and one-eighth | 7 1/4 to 7 3/8 | fifty-eight to fifty-nine |
| Large | twenty-three and a half to twenty-four | 7 1/2 to 7 5/8 | sixty to sixty-one |
| X-Large | twenty-four and three-eighths to twenty-four and three-quarters | 7 3/4 to 7 7/8 | sixty-two to sixty-three |
| XX-Large | twenty-five and one-eighth and up | 8 and up | sixty-four and up |
Why Small, Medium, and Large Disagree from Maker to Maker
Letter bands on caps are wider than on hats, because cloth gives where a blocked sweatband does not. One Large can be offered to a 7 3/8 head and a 7 5/8 head, and both will be told it is their size. They do not get the same fit; they get the same label.
Two practical rules follow. Trust the inch or centimeter figure on a size chart and treat the letter as a hint — if a listing gives you only a letter, ask for the number before you buy. And once a maker's Medium has fitted you, stay with that house for repeat orders: patterns are consistent within a line, far less so across the market. The flat caps we stock state a number or a centimeter range for exactly that reason.
How Should a Newsboy Cap Fit?
By the same four checks at the band, plus one of its own: the crown has to fall forward over the brim and drape, rather than balloon upward. A newsboy is cut from several panels joined at a button, with far more cloth in the crown than a flat cap, and that fullness is a pattern decision — it adds no circumference at all. A newsboy marked 7 1/4 measures 7 1/4 at the band, exactly like the slimmest ivy cap.
That catches people out in both directions. Too small, and the surplus cloth is pulled taut: the fullness disappears, the crown domes, and the button is dragged backward off center. Too large, and the crown slumps past the edge of the brim, so the cap reads as a beret with a bill. The button should sit near the center of the crown with the volume breaking forward — check that in profile, not head on.
The shallower relatives are less forgiving. An ivy cap is cut close with a short brim and no surplus cloth to hide an error, so a half size wrong shows instantly, while a full newsboy cap absorbs the same mistake visually and lets you walk out in the wrong size. If you are between sizes and want the safer buy, the fuller crown is it.
What the Fabric Does to a Cap's Fit
Two caps in the same stated size, one in tweed and one in cotton, do not fit the same way after a month.
- Wool and tweed. The most forgiving cloth: a slight give at the band with wear, good recovery, and enough body to hold the crown's shape. This is the material to choose if your measurement sits just over a size line.
- Cotton and linen. Almost no give, and they move the wrong way in the laundry. A hot wash can bring a cotton cap back a size small and warp the stiffener in the brim at the same time.
- Leather. It molds to the shape of your head over a few weeks without gaining meaningful circumference. Comfort improves; size does not change.
- Lined and ear-flap caps. A flannel lining or a folded-away ear flap takes up room inside the band. Try your usual size first, and if it marks your forehead, take the next one up.
That last point comes up more than any other once the weather turns, because ear-flap caps are among the strongest sellers at JJ Hat Center, a New York hat shop since 1911: three of our ten best-performing items overall are wool caps with ear flaps. Worth knowing before you order one in the size you wear in July.
Patterns matter as much as cloth. Stetson is our best-selling brand by a clear margin — roughly a quarter again as much in demand as the next name on our list — with Lierys behind it, and a Medium from one house can sit differently from a Medium from the other. Neither is wrong. It is simply the reason to note the number a cap states rather than the letter you usually buy.
Between Two Sizes: What Works on a Cap, and What Ruins One
Which way to round depends on how the cap is built. A structured newsboy, a lined cap, or anything with ear flaps: go up. A soft, unlined wool or cotton ivy cap that leaves no mark after fifteen minutes: take the smaller one, since it will relax about an eighth of an inch anyway.
A small gap can be taken up from the inside. A thin strip of felt or foam tucked behind the sweat strip at the front and sides — where a gap actually shows — brings a slightly large cap into line; add it in layers and rerun the four checks after each one. The habit is more common than people assume: cork sizing strips are the single best-selling item in our entire store, ahead of every hat and cap we stock, which tells you how many heads land between two sizes.
What not to do: do not wash a cotton cap hot in the hope of shrinking it into fit, because the shell, the lining, and the brim stiffener all move at different rates and the shape goes with them. And do not expect a cloth cap to stretch like felt. A felt crown is blocked over a form and can be eased with heat and a stretcher; a cap shell has no block behind it, so damp wear buys you a hair and nothing more. If the cap you already own has drifted out of fit, our guide to what to do when your hat feels too tight or too loose sets out the repairs that work and the ones that destroy a crown.
When the Letters Run Out: Larger and Smaller Heads
Above 7 5/8 the letters stop being useful. Many cap lines end at X-Large, and the heads that need more are left to hunt — so shop by the number or the centimeter figure from the start, and pass over any listing that will not say which head it was cut for. Caps are the best-selling category in our store, a touch ahead of hats, which is why the fit questions at the top and the bottom of the size range reach us so often.
Proportion deserves a thought once the size is settled. A large head carries a full newsboy crown well, because the volume balances the width; the same head under a shallow ivy cap reads as a lid set on too wide a base. Small heads work the other way: a short brim and a close crown, with the fullest newsboy patterns best avoided unless you want the cap to be the loudest thing you are wearing.
Frequently Asked Questions
Should a flat cap be tight or loose?
Snug. The band should press lightly and evenly all the way around, hold the cap still when you shake your head, and leave no red line on your forehead after fifteen minutes. If you can rotate the cap with one finger, it is too loose.
How do I measure my head for a flat cap?
Run a tailor's tape around your head about an eighth of an inch above the ears, across the middle of the forehead and over the ridge at the back of the skull, keeping it level. Pull it snug, measure three times, and use the largest reading. Note both the inch and the centimeter figure, since cap makers label in either.
How should a newsboy cap fit?
The same way at the band as a flat cap, with the full crown falling forward over the brim and the button sitting near the center. A domed crown with the button pulled backward means the cap is too small; a crown that slumps past the brim means it is too big.
Do flat caps stretch over time?
Wool caps relax roughly an eighth of an inch at the band over a season of regular wear. Cotton, linen, and leather caps barely change circumference at all, and no cap stretches a full size, so a cap that pinches now will still pinch next year.
What size flat cap should I buy if I am between Medium and Large?
Take the Large in a lined cap, a cap with ear flaps, or a structured newsboy, and the Medium in a soft unlined wool cap that leaves no mark after fifteen minutes. If the larger size turns out slightly loose, a thin strip of felt behind the sweat strip at the front and sides closes the gap.
