Sizing a Felt Hat: Head Fit and Stretch

Why the hat matters

In a hot room your scalp and hair take the most direct heat, especially near the ceiling and above the heater. A felt sauna hat adds a layer of insulation between that heat and your head, which lets you stay in longer and more comfortably. It also keeps your hair from drying out and protects it from the high temperatures.

The hat matters in both traditional and infrared rooms. In a traditional sauna, the air is hot and dry, so the felt blocks radiant heat from above. In an infrared room, the air is cooler, but the hat still protects your scalp from direct heat and keeps your hair from becoming brittle.

Beyond comfort, the hat is part of the ritual. Many bathers find that wearing one makes the heat easier to take and the whole session more relaxed. It is the simplest piece of sauna gear you will own, and the fit is the one thing that determines whether it works.

• Protects scalp and hair from direct heat
• Lets you stay in the sauna longer
• Works in traditional and infrared rooms
• Molds to your head over time

Measuring your head

You need a soft measuring tape, the kind used for sewing. If you do not have one, use a piece of string or a strip of paper, wrap it around your head, and then lay it flat against a ruler.

Place the tape so it rests just above your eyebrows and around the widest part of your head, usually at the crown. Keep it level all the way around. It should touch your skin but not press into it. Write down the measurement in inches or centimeters, whichever the hat maker uses.

Measure twice. Heads are not perfectly round, and a slightly different angle will give you a different number. Use the larger of the two readings if they differ, because you can always firm up the fit, but you cannot easily add material to a hat that is too small.

Reading size charts

Hat makers list sizes in either centimeters or inches, and sometimes both. The exact range varies by maker, so always check the specific chart for the hat you are looking at. If your measurement falls between two sizes, choose the smaller one. Felt stretches with wear and with exposure to heat and moisture, so a hat that is slightly snug at first will loosen over time. A larger size will stay loose and may not give you the close fit that keeps heat out.

Pay attention to whether the maker lists the measurement as head size or hat size. Some list the hat circumference, which is often a bit larger than the head measurement it is meant to fit. If the chart seems confusing, use the maker's contact form to ask.

Avoid guessing from hat styles. A wide-brimmed sun hat and a sauna hat are sized differently, and even two sauna hats from different makers can fit differently because of how they are cut and how thick the felt is.

How felt shapes with wear

Wool felt is an excellent material for the sauna because it insulates when wet, breathes, and takes on the shape of your head. The heat and moisture in the sauna soften the fibers slightly, and the pressure of the hat against your head encourages them to settle into a comfortable form.

This process takes a few sessions. During the first use, the hat may feel stiff and a touch snug. After two or three sauna visits, the felt will have relaxed and the hat will sit lower and feel more comfortable, without leaving red marks on your forehead.

You can help the shaping along by wearing the hat for a short time at home, away from the heat, before you take it into the sauna. The natural moisture and warmth of your head will begin the molding process without overstretching the felt.

If the hat is too loose after it has shaped, you can wet it and reshape it slightly, then let it dry in the desired form. This is rarely needed if you sized it correctly. For more on caring for felt, see our budget sauna gear guide.

• New felt is stiff and slightly snug
• Heat and steam soften the fibers
• The hat relaxes and fits lower after a few sessions
• Damp wool stretches; dry wool holds its shape

Fit and comfort

A correctly sized sauna hat should sit on your head without you having to hold it. It should cover your crown and reach down toward your ears and the nape of your neck. The brim, if there is one, should rest just above your eyebrows.

You should be able to move your head and tilt it forward without the hat sliding off. At the same time, there should be no pressure points or pinching. The hat should feel like a firm handshake, not a vise.

Your hair makes a difference. If you wear the hat over thick hair, it will feel tighter. Many bathers prefer to wear the hat directly on the scalp, with hair tucked inside. If you have long hair, you may want a hat with a deeper crown so that your hair does not spill out. Consider browsing 1-person sauna gear for hats that suit solo sessions.

Some hats come with a small string or tie that you can cinch under the chin. This is useful if you plan to move around in the sauna or if you have a head size between the maker's steps. The tie does not change the size, but it does prevent the hat from slipping.

Try the hat on with the same head covering you plan to use. If you wear a hair clip or a bandana, put those on first, then the hat. The fit will be slightly different, and you want the hat to work with your chosen setup.

Sizing for traditional vs. infrared

The same sizing method works for both traditional and infrared saunas, but you may prefer a different fit. In a hot traditional room, the hat is primarily there to block radiant heat, so a snug fit that stays in place is more important.

In an infrared room, the air is cooler and you may not feel the need for as much insulation. A slightly looser hat can still protect your scalp without adding extra warmth. If you plan to use the same hat for both, size it for the tighter of the two conditions, the traditional sauna, and it will work fine in the infrared room.

The hat does not need to be thicker for the infrared room. In either case, the wool felt does the same job: it holds the heat away from your head. What matters is that the hat covers the crown and stays put.

Whatever type of sauna you use, the felt hat protects your hair and scalp from the heat, and it keeps you comfortable enough to finish your session. It is one piece of gear you will reach for every time. Pair it with the right accessories: a cotton towel to sit on, a wool or cotton kilt, and leather or wool sandals. For a complete list, check our traditional sauna gear or infrared sauna gear guides.

What to pick for your use

Questions

How do I measure my head for a sauna hat?

Use a soft measuring tape. Wrap it around your head just above your eyebrows and around the widest part of the crown. Keep it level and snug. Compare that number to the maker's size chart.

Should I size up or down if I am between sizes?

Size down. Wet felt stretches with heat and steam, so a snug hat will relax and fit comfortably after a few sessions. A larger hat may stay loose and let heat reach your scalp.

How tight should a new felt sauna hat fit?

It should feel snug but not tight, with no pinching. You should be able to tilt your head forward without the hat sliding off. It will loosen slightly after the first several uses.

Will the hat stretch or shrink?

Wool felt stretches when damp and under pressure. Heat and steam soften the fibers, so the hat will relax and mold to your head. It will not shrink on its own in normal use.

Can I wear the same hat in traditional and infrared saunas?

Yes. The felt blocks heat in both room types. Size it for the traditional sauna if you use both, because the hotter environment makes a secure fit more important than in a cooler infrared room.