We must look into many factors while choosing a bicycle helmet. These factors include quality, type, durability, and safety measures. But the hardest part is to know and find the right helmet size. I was so confused when I was searching for my helmet size during my early cycling days. I sorted the issue after doing my research and experimenting with different helmets. So I can assume how difficult it can be for you to find the right helmet size. 

The trick to crack this problem is to gather enough knowledge, refer to a size chart, and know your helmet size. You are done if you know how to measure your helmet size and find one accordingly! Now, if you lack adequate information regarding this, I got you. 

Let me introduce you to the tips and tricks for finding the correct helmet size. I will provide size charts and give information to make the task easier. So, let’s start getting the right helmet size that fits perfectly!

3 Steps To Measure Bicycle Helmet Size:

You have to measure your helmet size to find the right one. Before going to the shop, do your homework. Measure your headband size. But even after that, you have to check the size by wearing it. All in all, you have to follow 3 steps to determine the correct helmet size. Otherwise, you may end up making mistakes. 

Here are the 3 easy steps to measure and get the right bicycle helmet size: 

Step 1: Measure Your Headband Size:

The first task is to measure your headband size. Use a measuring tape to do this task. If you don’t have one, use a rope or strap. Then measure on a ruler to mark the size. 

Hold the measuring tape to take the head circumference. Place it around your head, two fingers above your eyebrows, roughly an inch above. Take the measurement several times for accuracy. Note down the largest measurement you get. This is your headband size. 

Step 2: Try On The Bicycle Helmet:

If you buy online, refer to the size chart to know your right fit. After you get the delivery, you should check it once. If you buy from a showroom, you must try it first. 

Place the helmet on your head. If the size is correct, you won’t need to put much effort into fitting your head into it. But what if the helmet is too loose? You have to move your head sideways, backward, and forward. If the helmet moves too much, the helmet is loose, and you should go for a smaller one. 

You can try on adjusting the inner pads to improve the fit. But you have to ensure that the fit is correct. So let’s move to the next step. 

Step 3: Check The Fit:

If you think the size is more or less correct, try locking the buckles and adjusting the helmet straps. Put the inner pads in place too. Now fasten the straps. 

See if the front seam of the helmet is two fingers above your eyebrows. If yes, the size is okay. Tilt your head to check whether the helmet moves from place. The chin buckle should comfortably fit your chin. If the fitting is snug, the size is perfect for you. It should not be too tight or too loose.  

To confirm, check the position of the front seam of the helmet. See where it is placed. Then see if the helmet has fitted snugly in the head or not. 

Bicycle Helmet Size Chart For Kids:

First, I will mention the size chart for kids of different ages. If you are a parent, you can note this and carry it while buying a bicycle helmet for your kid

I have categorized kids into three sections:

  1. Baby: Below 1 year
  2. Toddler: 1- 4 years
  3. Youth: 5- 12 years

Here is the size chart for children that you can refer to:

Baby ToddlerYouth 
48 cm49 cm52 cm
49 cm50 cm53 cm
50 cm51 cm54 cm
51 cm52 cm55 cm
52 cm53 cm56 cm

It may seem like the difference is minor. It does look negligible in the chart. But the slightest difference would matter when it comes to a perfect fitting. Differences in a centimeter can make your kid feel uneasy. It may fit too tightly or loosely if the size is not correct. And that would not give an enjoyable experience to your kid. 

Bicycle Helmet Size Chart For Adults:

The helmet size for adults is different from the helmet size for kids. Though many adults ignore helmet size, they have uncomfortable and risky rides. When the size is not right, it disturbs a smooth ride. It can be risky, too, as a poorly fitted helmet can’t protect your head the best. This is why it is important to refer to a helmet size chart. 

Here is a bicycle helmet size chart for adults:

SizesMeasurement (CM)
Small52 cm
Small53 cm
Small54 cm
Small55 cm
Small56 cm
Medium57 cm
Medium58 cm
Medium59 cm
Medium60 cm
Large61 cm
Large62 cm
Large63 cm
Large64 cm

The size generally goes up to 63 cm. Only a few brands make helmets that have a 64 cm head size. The sizes do vary from brand to brand. But this chart will help you understand which category you should choose; small, medium, or large. 

3 Factors To Consider While Choosing Bicycle Helmet Size:

Several factors determine the right helmet size. Measuring the headband size is just one step. To make the fitting perfect, you must look into other factors. The headband size can’t always give you the right fit. I checked many factors before buying mine to get the correct fitting.

However, here, I am going to provide you with such 3 factors that you should consider for choosing the right bicycle helmet size: 

1. Shape:

No one may have told you that bicycle helmet shape can change the fitting. Not all shapes of helmets will suit you. This is why bicycle helmets are available in different shapes. 

Three common bicycle helmet shapes are:

  • Long Oval: This helmet has an elongated shape to the front and back ends of the bicycle helmet.
  • Intermediate Oval: This is the most common helmet with slightly elongated front and back ends. It has a moderately elongated and rounded shape. 
  • Round Oval: As the name suggests, it has a rounded shape, just like a skate-style helmet. It has a slight oval shape but is mostly round. 

If you have a long face, the long oval shape will suit you the best. The intermediate oval shape suits every head size most of the time. But it won’t be the best for a long-faced person. 

The round, oval shape is perfect for a round-faced person. Kids’ helmets are mostly rounded, as it is easy to balance. It fits smoothly on a round head. 

When the shape of the helmet is correct, the fitting is better. The helmet size is measured correctly when you consider the helmet shape. 

2. Hat Size:

You may notice that brands provide hat sizes in their size chart. Most companies mention the head circumference, hat size, and the size mark (small, medium, large). So you have to measure the head circumference and match it to the hat size in the size chart. 

To match the hat size, measure your head circumference with a measuring tape. You can use a string too and measure on a ruler. Take the measurement several times and mark down the number. Now you can move to the size chart to find your hat size. 

Here, I am providing you with two charts that mention standard hat sizes against head circumference measurements. 

Here is the hat size chart:

Size Head Circumference (CM)Hat Size
Small54- 55 cm6 ¾ – 6 ⅞ 
Medium56- 57 cm7- 7 ⅛ 
Large58- 59 cm7 ¼ – 7 ⅜ 
X-large60- 61 cm7 ½ – 7 ⅝ 
XX-large 62- 63 cm7 ¾ – 7 ⅞ 
XXX-large64- 65 cm8 – 8 ⅛ 

As you can see, a hat size is mentioned against a head circumference measurement. For accuracy, refer to the size chart to know your hat size. 

3. Fitting:

You may notice that sometimes you get the right size, but the fitting is not suitable. This is why I prefer to wear and test it before buying. 

Fitting depends on how you adjust the inner pads and fasten the straps and buckles. It often happens that the helmet sits too tightly on your head after fastening. This suffocates your head, restricts breathability, and puts pressure on your neck, chin, and rear head. Similarly, if the fitting is loose, it may fall off your head. 

To summarize, you need to see the fitting to get the right size. You may remember that I have mentioned to you to note the largest measurement you get after taking several measurements. This is generally the right size. The largest headband size allows you to make the fitting correct. You can adjust the pads and tighten the chin buckle to get the best fit. But when you get a smaller one, it can suffocate you. 

Therefore, even if the size seems correct, check the fit. If the bicycle helmet snugly fits your head, it is the right size. 

Related Questions:

How To Know That Your Bicycle Helmet Size Is Right? 

Even if you determine the correct helmet size, it may not always be right. The size would greatly depend on how it fits your head. If you are comfortable with it, then it is the right size. But if you feel uneasy, this is definitely not the right one for you. 

To know the right bicycle helmet size, you should wear the helmet. You have to see the fitting. I always emphasize perfecting the fitting as it gives ultimate ease and comfort. Remember that a good fitting doesn’t mean a tight fit. It has to snugly fit your head. 

If the helmet is too loose, it won’t stay in place and will tilt frequently. If it is too tight, then it will suffocate you. So after wearing the helmet, tilt your head all around. If the helmet stays in place, the size is correct. Now fasten the chin buckle. After that, put two fingers between the buckle and your chin. If you can do this smoothly, the fitting is right for you. 

To know your helmet size, you have to prioritize helmet fitting. If the fitting is good, this is the right bicycle helmet size. 

How To Adjust A Big Bicycle Helmet Size? 

Now, if you have bought the wrong helmet size and there is no way of returning it, don’t worry. I can’t ensure it would work if the size is too big for your head. If that is the case, you must exchange it or give it away. But if the helmet is only slightly larger than your size, I got you. 

You may notice that bicycle helmets come with extra pads in the package. Most companies provide some extra pads so that cyclists can adjust the fit. If the helmet is large on your head, it is time to use it. Fit those extra foams in the interior of the helmet. Now check the fit. If the helmet was only slightly large, fixing the extra pad would solve the issue. 

Besides, fasten the chin buckle tightly to make the fitting right. The biggest savior can be the occipital cradle at the back. If you adjust the radial correctly, it will give an excellent fit. The helmet won’t move from place, and you can be comfortable. This is how you can adjust the size of a big bicycle helmet. 

Do Bicycle Helmets Get Looser With Time? 

Bicycle helmets are sturdy. But they are made of stretchable materials. Especially the inner foams do stretch and expand over time. But the difference is minor. With time, bicycle helmets get looser, but nothing major. Also, it happens only if you use it regularly. 

Because bicycle helmets get looser with time, you shouldn’t get a small helmet size. This is a common mistake people make. Assuming it will expand, many people keep using a small helmet size. This is extremely harmful to your health. And since the expansion is insignificant, their expectations go down the drain.

My experience tells me that buying a small helmet size is horrible. It would suffocate and choke you. It is uncomfortable and can cause soreness, headache, and neck pain. When the helmet is that tight, you can’t expect it to stretch much. So, don’t make that mistake and try finding the right size. 


The trick is to measure the right helmet size and get the best fitting. Only then can you understand your perfect bicycle helmet size. And once you find it, you are ready to experience the ultimate comfort and bliss of cycling!

Find your bicycle helmet size and get the best one!