To measure your hat size without a tape measure, wrap a piece of string or a strip of paper around your head about 1 cm above your eyebrows and the tops of your ears, mark where the end meets, then lay it flat and measure the length with a ruler. That length in centimetres is your EU hat size, and the length in inches divided by π gives your US size, so a 57 cm head is EU 57, US 7 1/8 and UK 7.
Key takeaways
- Any non-stretchy string, ribbon, cable or paper strip works in place of a tape measure.
- Measure round the widest part of your head: across the forehead and just above the ears.
- No ruler? A sheet of A4 paper is 29.7 cm long and US Letter is 11 inches long, so either can act as a ruler.
- Your head circumference in cm is your EU size; US size = inches ÷ π; UK runs 1/8 smaller than US.
- Measure twice, and if you fall between sizes, choose the larger one.
What can you use instead of a tape measure?
You need something that bends round your head but does not stretch. Good options include:
- a piece of string, garden twine or ribbon;
- a phone charging cable or a shoelace;
- a long strip of paper, about 2 cm wide, cut or folded from a sheet of printer paper or newspaper.
Avoid elastic, wool that stretches and anything thick, such as a belt, as these give a less accurate reading. You will also need a pen or a small piece of tape to mark the length, and a ruler or something of a known size to measure it against.
How do you measure your head with string?
- Find the right line. The hat sits on the widest part of your head. Place the string across the middle of your forehead, about 1 cm (a finger’s width) above your eyebrows.
- Wrap it round the back. Take the string just above the tops of your ears and round the fullest part of the back of your head.
- Keep it level and snug. It should sit flat against your head without digging in. A mirror helps you check that it is not riding up at the back.
- Mark the meeting point. Pinch the string where the end meets the rest, then mark it with a pen or wrap a small piece of tape round it.
- Lay it flat and measure. Straighten the string along a ruler or one of the paper methods below, from the end to your mark.
- Repeat once. Measure a second time. If the two results differ, use the larger figure.
Measuring with a strip of paper
A paper strip works the same way and does not stretch at all. Wrap it round your head on the same line, mark where it overlaps, then unwrap it and measure from the end to the mark. If one strip is too short, tape two together before you start.
How do you measure the string without a ruler?
If there is no ruler in the house, standard paper and cards give you reliable lengths to measure against.
- A4 paper is 21 × 29.7 cm, so two long edges together make 59.4 cm.
- US Letter paper is 8.5 × 11 inches, so two long edges together make 22 inches.
- A standard bank or credit card is about 8.56 cm long and 5.4 cm wide.
Most adult heads measure somewhere between about 52 and 64 cm. With A4, lay the string along the long edge twice. If the string ends before 59.4 cm, measure the gap back from the corner with a card; if it runs past, measure the extra and add it. This gets you to within about half a centimetre, which is close enough to choose a size.
Can you measure a hat that already fits?
Yes, and it is a useful check. Take a hat that fits you well and run string round the inside of the sweatband, the band where the hat touches your forehead. The length of that circle is close to your head size.
Many hats also have a size printed on the label or inside the band. If yours says US 7 1/8 or 57, you already know your size. Letter sizes such as M or L are less useful, because each maker covers a slightly different range.
What is your hat size in cm and inches?
Once you have your measurement, converting it is simple. The EU size is your head circumference in centimetres, rounded to the nearest whole number. To find the US fitted size, convert to inches (divide the cm by 2.54) and then divide by π, which is about 3.14, and round to the nearest eighth. UK sizes are one eighth smaller than US sizes for the same head.
| Head (cm) / EU size | Head (inches) | US size | UK size |
|---|---|---|---|
| 53 | 20.9 | 6 5/8 | 6 1/2 |
| 54 | 21.3 | 6 3/4 | 6 5/8 |
| 55 | 21.7 | 6 7/8 | 6 3/4 |
| 56 | 22.0 | 7 | 6 7/8 |
| 57 | 22.4 | 7 1/8 | 7 |
| 58 | 22.8 | 7 1/4 | 7 1/8 |
| 59 | 23.2 | 7 3/8 | 7 1/4 |
| 60 | 23.6 | 7 1/2 | 7 3/8 |
| 61 | 24.0 | 7 5/8 | 7 1/2 |
| 62 | 24.4 | 7 3/4 | 7 5/8 |
For example, a 22.4-inch head divided by 3.14 gives about 7.13, which rounds to US 7 1/8 and UK 7. You can type your own measurement into our hat size chart to get the US, UK and EU sizes worked out for you.
How to get an accurate reading at home
Small slips make a difference, because each step between hat sizes is only about one centimetre of head size. These habits help.
- Wear your hair as usual. If you often wear a bun, braids or thick hair under a hat, measure with your hair styled that way.
- Do not pull tight. A string pulled hard gives a smaller number than the hat will need.
- Ask someone to help. A second person can check the string is level at the back, which is hard to see yourself.
- Measure in centimetres if you can. It gives you the EU size directly and makes rounding easier.
The same string-and-ruler method works for other body measurements too. Our guide on how to measure yourself for clothes covers chest, waist and other key points.
What if you are between hat sizes?
Go up to the larger size. A slightly big hat can be made snugger with hat sizing tape behind the sweatband, but there is no easy fix for a hat that is too small. For more on how a hat should feel once it is on, and how to adjust one that is a little loose, see the hat guides in the Luxeurs Journal.
FAQs
Can I use my phone to measure my head?
A phone screen is too short to wrap round your head, but you can use a charging cable as the string, then measure it against a ruler or a sheet of paper as described above.
What is the average hat size?
Head sizes vary widely, so there is no single answer that fits most people. Many adult heads fall roughly between 54 and 60 cm, but plenty are smaller or larger, so it is always worth measuring rather than guessing.
Is hat size the same as head circumference?
In EU sizing, yes: a 58 cm head is a size 58. US and UK sizes are worked out from the circumference, so the numbers look different but describe the same head.
How do I convert my hat size from US to UK?
Take one eighth off the US size. A US 7 1/4, for example, is a UK 7 1/8, and both fit a 58 cm head.
Does a cap use the same size as a fedora?
Fitted caps use the same US sizing, so your measurement works for both. Many caps have an adjustable strap instead, which covers a range of head sizes.