US = inches ÷ π
The US fitted size is the diameter of your head in inches — head circumference divided by pi, rounded to the nearest ⅛ inch. That is why sizes look like 7 1/4 or 7 5/8.
Measure · Convert · Done
Hat sizes, made to measure
Measure your head, see your size in US, UK, EU and S–XL — instantly, with full explanations.
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- cm · inches · fractions
- US · UK · EU · S–XXL
- Printable tape
Hat size converter
Enter your head measurement to see your size in every system at once.
Outside the standard adult range
US fitted
head
UK
= US minus 1/8
EU
= head in cm
Letter
varies by brand
Adults measure roughly 53–65.4 cm around the head. Letter sizes are a general guide — they vary by brand.
The full chart
Hat size chart — every system side by side
Find your head circumference in centimetres or inches and read across to the US fitted size, the UK size, the EU size and the closest letter size. Rows are clickable for a size-by-size breakdown.
| US | UK | Head (cm) | Head (inches) | EU | Letter |
|---|---|---|---|---|---|
| 6 5/8 hat size | 6 1/2 | 53.0 | 20 7/8 | 53 | S |
| 6 3/4 hat size | 6 5/8 | 53.9 | 21 1/4 | 54 | S |
| 6 7/8 hat size | 6 3/4 | 54.9 | 21 5/8 | 55 | S |
| 7 hat size | 6 7/8 | 55.8 | 22 | 56 | M |
| 7 1/8 hat size | 7 | 56.8 | 22 3/8 | 57 | M |
| 7 1/4 hat size | 7 1/8 | 57.7 | 22 3/4 | 58 | L |
| 7 3/8 hat size | 7 1/4 | 58.7 | 23 1/8 | 59 | L |
| 7 1/2 hat size | 7 3/8 | 59.6 | 23 1/2 | 60 | XL |
| 7 5/8 hat size | 7 1/2 | 60.6 | 23 7/8 | 61 | XL |
| 7 3/4 hat size | 7 5/8 | 61.5 | 24 1/4 | 62 | XXL |
| 7 7/8 hat size | 7 3/4 | 62.5 | 24 5/8 | 63 | XXL |
| 8 hat size | 7 7/8 | 63.5 | 25 | 64 | XXL |
| 8 1/8 hat size | 8 | 64.5 | 25 3/8 | 65 | XXL |
| 8 1/4 hat size | 8 1/8 | 65.4 | 25 3/4 | 65 | XXL |
Measuring
How to measure your head for a hat
- 1Place the tape. Wrap it around your head so it crosses the middle of your forehead, just above the ears and eyebrows — exactly where the hat band will sit.
- 2Keep it level and snug. Not tight — the tape should lie flat against the skin all the way around, without pinching.
- 3Read and repeat. Note where the tape meets, then measure twice more and keep the largest reading. Enter it in the converter above.
No tape measure at all? Our printable paper measuring tape prints at true size on A4 or Letter paper, with a calibration check.
How it works
How the hat size conversions work
UK = US − 1/8
UK sizes use the same fitted system but run exactly one eighth smaller. A US 7 1/4 equals a UK 7 1/8 — every row of the chart above shows the pair.
EU = cm
European sizes are simply your head circumference in centimetres, rounded to a whole number. A 57.7 cm head is an EU 58.
Choosing
Fitted vs adjustable hats
Fitted
Exact numerical sizes in eighth-inch steps. No give, no stretch — the chart above applies. If you are between sizes, go up.
Stretch-fit (S/M, M/L)
Elastic blends cover a span of sizes. Our fitted hat size chart lists the combined sizes alongside the fitted fractions — the New Era hat size chart page shows how the biggest fitted brand maps the same numbers.
Adjustable (snap, strap, buckle)
One size that you cinch to fit. Measuring still helps: pick the crown depth and the position of the strap that suits your head.
Letter sizes vary by brand; check the brand's own chart.
By wearer
Men's, women's & youth hat size charts
The table above is one chart for everyone — where sellers split it, a men's hat size chart is mostly the dense middle of the range (US 7–7 3/4, for adult heads of 56–61 cm) and women's listings cluster just below it. Neither is a different system: every fitted fraction still comes from inches ÷ π.
For children it is a range question, not a formula question. Our youth hat size chart covers newborn medians (~34 cm) to the adult-size bridge at 53 cm, with WHO/CDC-sourced age bands — and the advice that beats every one of them: measure the child's head.
Answers
Hat size FAQs
What is the average hat size?
Most adult men measure about 58–59 cm around the head, which is a US fitted size of roughly 7 1/4 to 7 3/8. Most adult women measure about 55–57 cm, or US 6 7/8 to 7 1/8. Averages are only a starting point — measure your own head before buying any fitted hat.
What should I do if I'm between two hat sizes?
Go up one size when the hat is non-adjustable. A slightly large hat can be tightened with the internal sweatband or a strip of hat-sizing tape, but a hat that is too small cannot be stretched out comfortably. When your measurement is close enough to a chart size, this site simply returns that size instead.
What is the difference between US and UK hat sizes?
Both systems are based on head diameter, so the numbers look similar — but UK sizes run exactly one eighth smaller. A US 7 1/4 is a UK 7 1/8, and a US 7 is a UK 6 7/8. If a seller lists UK sizes, subtract one eighth from the US size you would normally wear.
Does head size change over time?
Yes, slowly. Heads grow with age and can also be affected by hairstyle, weight changes and even heat. Measure again before each new hat purchase rather than trusting a size remembered from years ago, and measure with the hairstyle you expect to wear under the hat.
Can I measure someone else's head, for a gift?
Yes. Wrap the tape around their head so it sits just above the ears and eyebrows where their hat would rest, keep it level and snug, and read the number where it meets. If they are curious, tell them why — or use our printable paper tape and ask them to measure themselves.
Are men's and women's hat sizes different?
The mathematics are identical because hat sizing comes from head circumference, not gender. The differences are in the styles: women's hats are more often sold with combined letter sizes such as S/M or M/L, while men's fitted caps more often use exact fractions like 7 1/4.
Do 'one size fits all' hats really fit everyone?
Not quite. Stretch-fit and adjustable hats cover a span of head sizes — that is why this site shows letter bands next to the exact fitted sizes. They fit most heads somewhere in the 54 to 63 cm span, but for a precise fit it always helps to measure first.
How to measure hat size for a chart?
Wrap a soft tape measure around your head where the hat will sit — just above the ears and eyebrows. Keep the tape level and snug but not pinching, read the circumference in centimetres or inches, and measure three times, keeping the largest reading. Then find that measurement in the row of the hat size chart above and read across to the US, UK, EU and letter sizes, or type it into the converter at the top of this page. No soft tape? Our printable paper tape prints at true size on A4 or Letter.
How to use a hat size chart?
Start with one number: your head circumference. Find it in the head-size column, then read along that row — the US fitted size in eighths of an inch, the UK size (exactly one eighth smaller than the US figure), the EU size (your centimetres, rounded) and the closest letter size from S to XXL. Rows sit about 1 cm of head apart, so if you land between two rows, round up to the larger size. Every row of the chart above is clickable and opens a full breakdown page for that size.
How do I convert inches to hat size?
Divide your head circumference in inches by pi (about 3.1416) and round to the nearest eighth of an inch — that result is your US fitted hat size, because fitted labels are head diameter, not circumference. Example: a 22 3/4 inch head is 22.75 ÷ π ≈ 7.25 inches across, so US size 7 1/4 — the same head is 57.9 cm, EU 58. Working backwards, a US 7 1/4 label means a head circumference of about 22 3/4 inches (7.25 × π), or 57.9 cm. The chart above runs both directions for you.
What is a size 8 equal to?
A US fitted size 8 is one of the largest fitted sizes, cut for a head circumference of 25 inches — about 63.5 cm around. The same head is a UK 7 7/8 (UK labels run one eighth smaller than US) and EU size 64 (the same centimetres, rounded). In letter sizing it falls in the XXL band, which covers roughly 61 to 66 cm. Size 8 sits near the top of the chart, which ends at US 8 1/4 (25 3/4 in, 65.4 cm).
How to size a hat smaller?
Match the method to the material. Cotton and polyester caps shrink slightly when you soak the crown in hot water and air-dry — test the fit as it dries. Wool felt hats can be steamed, then worn while warm and damp so they conform smaller, and reshaped as they cool. The reversible fix for any hat is hat-sizing tape or thin foam strips under the sweatband, which tighten the fit by a size or two and come out again. One caution: a hat more than a full size too large is rarely worth rescuing, and dryer heat can ruin the shape.
How should a good hat fit?
Check three things. Position: the sweatband rests just above your ears and eyebrows, level all the way round — never pressed down over the ears. Hold: the hat stays on when you nod briskly or bend down; a little movement in strong wind is normal, but it should not slide while you walk. Comfort: a snug grip with no pressure points and no deep red mark across the forehead after an hour. A fitted hat should need a firm pull to come off; stretch-fit and adjustable styles run a shade looser, but a hat that moves over your ears is a size too big.
Dig deeper
Every size, in detail
Each size gets its own page with direct answers, neighbouring sizes and conversions — for example,7 5/8 hat size in cm orwhat size hat is 58 cm.
Kids' hat size chartBabies & children, cited dataCowboy hat size chartWestern & long-oval headsBeanie size guideStretch fits & rangesBucket hat sizingRelaxed one-size hatsFedora size guideFitted & letter sizesCrochet hat size chartFor makers, with negative easeNew Era sizes (unofficial)59FIFTY & 39THIRTY explainedFlexfit sizes (unofficial)Stretch-fit S/M–XL mappingStetson sizes (unofficial)Western letters & fractions