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How to size and buy a motorcycle helmet

May 25, 2019

Choosing a helmet isn't just figuring out your size and your favorite paint job. It's buying a helmet that will actually work to protect your head in the event of an impact.

There's no sugarcoating it: Helmet fitment determines just how much safety your helmet can provide. In fact, a DOT safety rating is only valid for a correctly sized helmet!

When your helmeted head experiences an impact, the impact-absorbing liner is designed to manage those forces. But if there’s too much of a gap between the helmet and your head, you're basically setting yourself up to get smacked by your own safety gear. Also, some helmets have slip liners built in, like Bell's MIPS system, to reduce injuries from rotational forces. If the liner doesn’t fit well against your head, it can’t function as intended. On the other hand, if the helmet is too tight because there's too little of a gap, the helmet will simply be uncomfortable. It'll become distracting or painful or you'll just stop wearing it. A good fit prevents both problems and allows the helmet to do its job.

All helmets are not created equal with respect to fitting your noggin. That doesn't mean you have to pay big bucks to get good protection and fit. There are plenty of options on the market for all price points, head shapes, and riding styles. You just have to pay attention when picking out your next lid.

Feeling overwhelmed? Choosing the right helmet doesn't have to be a daunting task with our full guide to walk you through it. If you can shake your head, use a measuring tape, and find a friend to lend a hand, you can do this!

Ready to get started? The steps to choosing the right helmet are simple:

  1. Choose a helmet style.
  2. Determine your head shape and size.
  3. Try on the helmet.
  4. Check for proper fit.
  5. Wear the helmet for about half an hour.
  6. Still feels right? Go ride!

1. Choose a helmet style

Motorcyclists have never had so many helmet choices available. While it’s fantastic to have all these options, it can be overwhelming to find the perfect one. Where to start? Speaking broadly, there are five basic types of helmets you should be familiar with before making your decision.

Open face motorcycle helmet
Open face helmets put your face in the wind. RevZilla photo.

First is the open face helmet, which is the least restrictive and least protective. Open face helmets flow tons of air, since the helmet’s shell does not cover the rider’s chin or face, hence the name. An open face helmet could be a “half” helmet, which just covers the top of your skull, or a “three-quarter” helmet, which covers everything except the rider’s face. Open face helmets tend to be less expensive than other types of helmets, and they’re usually short on features as well. You’ll typically see these helmets worn by riders on cruisers, retros, and classics.

Full face motorcycle helmet
When most people think of a motorcycle helmet, they're imagining something like this. RevZilla photo.

The full face helmet, on the other hand, totally encloses the rider’s head. A face shield protects the rider’s nose and eyes, and an extension of the shell called the chinbar covers the bottom of the rider’s face. Full face helmets are the least ventilated, but the most protective against impacts and the elements. They’re also the quietest helmets available. A full face helmet is the only option if you aspire to take your helmet to the track. Full face helmets are common around every kind of street bike. 

Modular motorcycle helmet
This modular helmet looks like a full face, but hit that red release, and the front hinges out of the way. RevZilla photo.

Modular helmets are a subset of full face helmets. These helmets use a hinged mechanism to swing the chinbar and face shield out of the way when the rider hits the release, instantly converting the full face helmet into an open face helmet. This modularity gives the helmet its name. Modular helmets let riders choose between the benefits of both open face and full face helmets, all in one. For example, a touring rider might want full face protection on the highway, but the ease of an open face while grabbing lunch at a rest stop. (Note that modular helmets are not intended to be used in the open position while riding.)  With modulars, the tradeoff for its convenience is often increased weight and noise over conventional helmets, though modular helmets are improving every year. Modulars are especially popular with the touring and commuter crowds.

ADV motorcycle helmet
ADV helmets combine elements of dirt and street helmets. This hybrid design makes for a versatile helmet. RevZilla photo.

If your rides take you on- and off-road, consider an ADV, or adventure, helmet. ADV riders transition from the street to the trail in a single ride, so their helmets combine features for both disciplines. On the street, an ADV helmet offers a face shield and a street-legal safety rating. For riding in the dirt, they mimic a dirt helmet with a peak (like the bill on a cap over the eyes), lots of ventilation, and compatibility for goggles. Of course, their hybrid nature makes for some compromises, but there’s no better choice if your adventures incorporate both street and trail. ADV helmets are most at home with dual-sport and ADV riders.

dirt or off-road helmet
The dirt helmet is a highly specialized piece of gear. RevZilla photo.

Finally, there’s the dirt helmet, made exclusively for off-road riding. Note that these helmets do not require a Department of Transportation (DOT) rating, so they might not be street-legal. Dirt helmets feature plenty of airflow, plus a large peak to keep roost out of the rider’s eyes. They’re intended to be worn with goggles. (Goggles are almost always sold separately.) They’re exceptionally light, though they sacrifice face shields and other comforts to make that possible. A dirt helmet is designed for off-road riding, so if you’re going to be riding on the street, it's recommended that you choose something else.

determining your head shape
Joe's head shape is intermediate oval. RevZilla photo.

2. Determine your head shape and size

Hopefully, one of the helmet categories sounds right for you. Now that you have a direction, it’s time to figure out your head shape. People generally fit into one of three head shapes: long oval, intermediate oval, and round oval. To find out what you’ve got, ask a friend to take a photo of your head from above. Flatten your hair down as much as possible, because it can obscure your head’s shape. Looking at the picture, is your head almost round (round oval), or is it long and thin (long oval)? Somewhere in between (intermediate oval)? In the United States, intermediate oval is the most common, but check to be sure before moving on to sizing. You can filter your results on RevZilla to select only helmets that match your head shape.

determining your helmet size
How to measure your head size. RevZilla photo.

Now, find your helmet size. Helmet sizing is a little strange for most people, since we don’t use head size as commonly as waist size, shirt size, or shoe size in everyday life. Fortunately, it’s not hard to figure it out. Ask your friend to measure your head’s circumference with a soft tape measure. The tape should run above your eyebrows and around the back of your head, including the widest part. A piece of string will do in a pinch. Just lay it against a ruler after measuring to figure out the length. (You can do this yourself, but we really recommend asking a friend to get the most accurate measurement possible.) Compare your result against a helmet’s size chart to determine which size you need to order. RevZilla publishes both metric and Imperial measurements, so don’t sweat the conversions.

3. Try the helmet on

So you know what style of helmet you’d like, as well as your measurements and head profile. That should narrow your search down to a range of helmets that will work. Time to order! When the helmet comes in, put it on, keeping in mind that you might have to grab the straps and spread them apart to slip the helmet over your head. Helmets aren’t designed to be comfortable while your head is passing through the pads. You might need to adjust your ears, too. That’s totally normal, just like adjusting your sock after putting a shoe on. The focus should be on fitment with the helmet in place.

4. Check for proper fit

With the helmet on, how should it feel? Any severe discomfort means you should try another helmet. If you ordered an unwearable helmet after following the steps above, consider rechecking your size and shape assessments. You shouldn’t be that far off the mark if you measured accurately, checked the size chart, and paid attention to the product description/video.

If the helmet fits as it should, you should feel the cushions against your cheeks. They’ll be pushed up a little, like “chipmunk cheeks.” (Note: Open face helmets do not have cheek pads, so they will not give this effect.) Next, grab the chin bar and move it around. Your cheeks should move, not the helmet. If it’s sliding, go down at least a size. If the helmet’s a little on the tight side, keep in mind that most helmet liners break in 15 percent to 20 percent after the first 15 to 20 hours of riding.

wear the helmet
Wear the helmet a while to see if any pressure points develop. If the helmet causes a pressure point that's uncomfortable after 15 minutes, it will be surprisingly painful after a three-hour ride. RevZilla photo.

5. Wear the helmet for about half an hour

Leave the helmet on for 15 to 30 minutes. Just sit, maybe watch your favorite TV show. (How about some RevZillaTV?)  Pressure points are what you’re looking for. Tightness is OK, but if you feel like you need to get the helmet off to stop the pain, that’s not the helmet for you. Discomfort is most common in two places: directly at the forehead, or just above the temples. If you have a big red line across your forehead after removing the helmet, try something else. That helmet is not long-oval enough. If you feel the helmet squeezing your temples, it isn’t round enough for you. Keep in mind that this half-hour period should be spent off the bike. We can’t take returns on helmets once you ride with them!

fasten the helmet chin strap
Don't forget the strap! A helmet needs to be secured so it doesn't fly off in a crash. RevZilla photo.

6. Still feels right? Go ride!

Wearing a helmet just won’t be as comfortable as sitting around your house without one. That said, you should feel decently comfortable wearing the helmet for a half hour at a time. Make sure you spend some time in the helmet to pass that 15-20 hours of break-in. The helmet will mold to your head somewhat, making for an even better fit. Enjoy your new helmet!

Common problems

Our friendly Gear Geeks get calls all the time about helmet fitment. Here are a few of the most frequent issues.

“My ears get folded over when I put my helmet on.” That’s normal. Watch a MotoGP race and you’ll even see the pros adjusting their ears as they gear up. As long as you can push your ears back to a natural position and your ears do not hurt, you’re good to go. Again, it’s all about how the helmet fits once it’s actually in position. 

“I really can’t figure out my head shape.” Did you actually get a friend to help you get that bird’s-eye view of your head? Also, did you actually flatten your hair as much as possible? That should be all it takes. If you really can’t figure it out, intermediate oval is probably your best bet.

“I can’t even get my head into the helmet, even though the chart said this was my size!” That might actually be your size. Some helmets have more neckroll cushioning than others. Hold the helmet by the two straps, with your thumbs pressing the straps against the helmet. Gently spread the helmet’s opening a little, then try pulling it over your head. If it still doesn’t fit, don’t force it. Stop and try the next size up.

"I wear glasses or sunglasses when I ride. Does that change what helmet I order?" Probably not! Most helmets these days have some sort of accommodation for eyeglasses. If you wear glasses when you ride, try them when you test fit. Don’t size up if everything fits perfectly except your glasses. Consider another model helmet, a different pair of glasses, or contact lenses. If those glasses are just for blocking the sun, a drop-down sun shield might be a good solution for you.

"I think my helmet is too tight." If you can’t put it on, at all, then that’s obviously too tight. If you can get it on, but it hurts where it presses against your head, that’s also too tight. If it’s snug all around, too snug to chew gum, that’s about right. Don’t forget about that 15 percent to 20 percent break-in that will occur.

"I think my helmet is too loose." If you can’t pass the “chipmunk cheeks” and chin bar tests (see step four above), you’re correct.

"I heard I can get different pads for my helmet, or modify the pads I have to get the fit I want. What’s up with that?" It’s true, you can dial in the fit by altering the comfort pads inside your helmet. Not all helmets offer this feature. If your helmet is almost perfect, even after the break-in period, you can make slight adjustments with different pads and liners. The pad size is usually marked on the back, so you’ll have to remove them to see what you’ve got. Some helmet manufacturers, like Arai, pre-cut their cheekpads so you can peel layers off to buy clearance.

That's about all there is to it! You should have everything you need to find and fit your own helmet. All that measuring and testing will be worth it when you reach for that perfectly broken-in helmet on your next ride.