Selecting the right bike size doesn’t have to be complicated. This guide breaks down how different bikes are measured. It also offers fitting tips for men, women and kids.
A professional fitting at a bike shop is always ideal. But not when you’re buying bikes online or through a marketplace.
So, if that’s not an option, use this guide to assess your needs and choose a suitable size.
If you want to jump straight to sizing, use the table of contents to find your section. If you’d rather get the full context and tips, read on for the complete guide.
Contents
What Size Bike Do I Need?
Bike sizing might seem tricky because there isn’t a universal system that works for every bike and every rider. Adult bikes are usually sized by frame, while kids’ bikes use wheel size, and road and mountain bikes follow their own standards.
A professional bike fitting at a local shop will give you the most accurate results. But if you’d rather start on your own, the charts and tips in this guide will help you narrow down the right size.
What and How to Measure
If you want to know what size bike frame do you need, you need two measurements: height and inseam.
Why inseam matters: it ensures the right standover height—you want 1–2″ clearance between your crotch and the top tube for comfort and safety.
What you need: tape measure, book, ~30 seconds.
- Height: stand against a wall, place a book on your head, measure floor to book.
- Inseam: shoes off, feet hip-width, measure from floor to crotch.
Write them down, and you’re ready to size your bike.
Is Women’s Bike Sizing And Different?
Some bicycle brands produce women-specific models, often with features like narrower handlebars, shorter stems, or saddles designed for female anatomy. These adjustments can improve comfort, but when it comes to sizing, there is no fundamental difference between men’s and women’s bikes.
Both use the same frame measurements, and the same charts apply to all adult riders. The key is to start with the correct frame size and then fine-tune the fit with components such as the saddle, stem, or handlebars.
This approach ensures women get just as precise and comfortable a fit as men, whether they choose a women-specific design or a standard model.
Differences in Bike Types
Bike sizing isn’t universal.
Sizing can differ between bike types and even from one brand to another.
Road bikes and mountain bikes often use different numbers for the same rider height, which can be confusing. In the past, sizes were based on frame parts like the seat tube.
As bike designs evolved, manufacturers updated their systems to match modern geometry.
The idea was to simplify things, but because some brands still use older methods, you’ll see mixed sizing standards today. Always check the chart for your specific bike style to make sure the fit is right.
Important Info About Bike Size Charts
The charts below cover road, mountain, hybrid, and kids’ bikes.
There’s no single chart that works for every brand or style, since each uses slightly different measurements.
Use these charts as a starting point to find your general size, then double-check with the brand’s own chart for the most accurate fit.
Each chart in this guide works as a simple bike size graph, helping you compare height, inseam, and frame size at a glance. So let’s start
Road / E-Road / Gravel / Adventure Bike Size Chart
Road, gravel, and adventure bikes all use centimeter-based frame sizing, and their charts overlap closely. While gravel and adventure frames may have slightly different geometry for stability and comfort, the starting point is the same as for road bikes. Use the chart below to match your height with the right frame size.
| Frame Size (cm) | Rider Height (ft/in) | Rider Height (cm) | Alpha Size |
|---|---|---|---|
| 47–48 cm | 4’10”–5’0” | 148–152 cm | XXS |
| 49–50 cm | 5’0”–5’3” | 152–160 cm | XS |
| 51–53 cm | 5’3”–5’6” | 160–168 cm | S |
| 54–55 cm | 5’6”–5’9” | 168–175 cm | M |
| 56–58 cm | 5’9”–6’0” | 175–183 cm | L |
| 58–60 cm | 6’0”–6’3” | 183–191 cm | XL |
| 61–63 cm | 6’3”–6’6” | 191–198 cm | XXL |
This gives you a good ballpark reference, but geometry can differ between brands, so it’s always worth checking the specific model chart for the best fit.
If you fall between two sizes, consider these tips:
Size up if:
- Your arms are long, or your wingspan is greater than your height
Size down if:
- You want a bike that feels lighter and stiffer (good for sprinters)
- You prefer a more upright riding position
MTB, E-MTB & Fatbike Size Chart
Don’t rely on S/M/L labels—they vary widely by brand.
Size mountain bikes by measurements: start with reach and stack, then confirm effective top tube and standover in the brand’s geometry chart.
Hardtails and full-suspension bikes can feel different at the same “size” (full-suspension often a touch shorter in feel due to suspension design and sag), so compare the numbers, not the letters. With modern geometries, tube lengths alone aren’t useful.
Use the chart below to match your bike size for height with the recommended mountain bike frame measurements, keeping in mind that geometry can differ slightly between brands and between hardtail and full-suspension models.
MTB, E-MTB & Fatbike Size Chart
| Frame Size (in) | Alpha Size | Rider Height (ft/in) | Rider Height (cm) | Leg Inseam (in) | Leg Inseam (cm) |
|---|---|---|---|---|---|
| < 14″ | XS | 4’10″–5’1″ | 148–158 cm | 24″–29″ | 61–73 cm |
| 15″–16″ | S | 5’1″–5’5″ | 158–168 cm | 25″–30″ | 63–76 cm |
| 16″–17″ | M | 5’5″–5’9″ | 168–178 cm | 26″–31″ | 66–78 cm |
| 17″–18″ | L | 5’9″–6’0″ | 178–185 cm | 27″–32″ | 68–81 cm |
| 18″–19″ | XL | 6’0″–6’3″ | 185–193 cm | 28″–33″ | 71–83 cm |
| 19″+ | XXL | 6’1″–6’6″ | 193–198 cm | 29″–34″ | 73–86 cm |
This gives you a good ballpark reference, but geometry can differ between brands, so it’s always worth checking the specific model chart for the best fit.
What About MTB Wheel Sizes?
Mountain bikes today come in three main wheel sizes: 26″, 27.5″, and 29″. The older 26″ size is now rare but still offers a very agile, playful feel for smaller riders. Most modern bikes use 27.5″ or 29″, and your choice depends on both height and riding style.
- Smaller riders often find 27.5″ wheels easier to handle and more responsive on twisty trails.
- Taller riders usually benefit from 29″ wheels, which improve stability, roll over obstacles smoothly, and keep speed better.
- 26″ wheels may still appeal to riders who want maximum maneuverability and quick handling, though they’re less common today.
In general, larger wheels provide smoother handling at speed and better efficiency, while smaller wheels favor sharp handling and agility. Beginners can safely follow the first option in the chart, while advanced riders might experiment with different sizes to match their style. The best way to judge handling for your height and skills is to test ride and compare.
When to Size Up or Down on a Mountain Bike
If you fall between two mountain bike sizes, think about your riding style.
- Size up if you want more stability at speed, better traction on climbs, or extra room in the cockpit.
- Size down if you prefer quicker handling, a more playful ride, or a slightly lighter bike for technical trails.
Geometry varies by brand, so always compare charts and, if possible, test ride both sizes to feel the difference.
Why Do Mountain Bikes Have So Many Specifics in Frame Measuring?
In the early days, MTBs were sized by seat tube length, which gave a fair idea of standover height.
That worked when frames were simple and close to road bike geometry. As designs changed—sloping top tubes, dropper posts, longer wheelbases—the seat tube stopped being a reliable guide.
Today, brands usually assign a frame size (XS, S, M, L, etc.), but these sizes don’t always match across companies. That’s why geometry charts list extra numbers like reach and stack. While you don’t measure these yourself at home, they let you compare how different bikes in the same “size” will actually feel.
Start with the frame size for your height and inseam, then use reach and stack to fine-tune which brand’s sizing works best for you.
Hybrid / E-Hybrid / City / Commuter Bike Size Chart
Hybrid bikes, such as commuters and fitness models, are versatile and usually budget-friendly.
Most brands list them in Small, Medium, or Large sizes, but some still use inches for frame measurements. Because sizing can vary, it’s best to check the geometry chart for each model.
Start with your height as a guide, then fine-tune the fit with adjustments like saddle height or stem length.
| Frame Size (in/cm + Alpha) | Rider Height | Leg Inseam |
|---|---|---|
| 14″ / ~47 cm — XS | 4’10″–5’1″ 147–155 cm | 24″–29″ 61–73 cm |
| 15″ / ~48 cm — S | 5’1″–5’5″ 155–165 cm | 25″–30″ 63–76 cm |
| 16″ / ~50 cm — M | 5’5″–5’9″ 165–175 cm | 26″–31″ 66–78 cm |
| 17″ / ~52 cm — L | 5’9″–6’0″ 175–183 cm | 27″–32″ 68–81 cm |
| 18″ / ~54 cm — XL | 6’0″–6’3″ 183–191 cm | 28″–33″ 71–83 cm |
| 19″ / ~56 cm — XXL | 6’3″–6’6″ 191–198 cm | 29″–34″ 73–86 cm |
Use this as a ballpark reference—geometry can vary across brands, so double-check specific model charts.
Size up when:
- You have long arms or legs and want more reach.
- You ride long distances and prefer a stretched, aerodynamic position.
- You want extra stability at higher speeds.
Size down when:
- You prefer a lighter, stiffer frame for sprinting.
- You like a more upright riding position.
- You want sharper handling for technical courses.
Kids & Junior Bike Size Chart
Kids’ bikes are sized by wheel diameter, which makes them easier to understand than adult bikes.
A 12-inch bike has 12-inch wheels, a 16-inch bike has 16-inch wheels, and so on. Height is the main factor, but age can be a useful guide too.
Always check that your child can stand over the frame comfortably and reach the handlebars and brakes with ease. Use the chart below as a starting point, then confirm the fit with an in-person test ride whenever possible.
| Tire Size | Age Range | Rider Height (ft/in) | Rider Height (cm) | Leg Inseam (in) | Leg Inseam (cm) |
|---|---|---|---|---|---|
| 10″ | 2 years | 2’9″–3’1″ | 85–90 cm | 12″–14″ | 30–35 cm |
| 12″ | 3–4 years | 3’1″–3’3″ | 90–100 cm | 14″–17″ | 35–42 cm |
| 14″ | 4–5 years | 3’3″–3’7″ | 100–110 cm | 16″–20″ | 40–50 cm |
| 16″ | 5–6 years | 3’7″–3’8″ | 110–115 cm | 18″–22″ | 45–50 cm |
| 18″ | 6–8 years | 3’8″–4’0″ | 115–120 cm | 20″–24″ | 50–60 cm |
| 20″ | 7–9 years | 4’0″–4’5″ | 120–135 cm | 22″–25″ | 55–63 cm |
| 24″ | 9–11 years | 4’5″–4’9″ | 135–145 cm | 24″–28″ | 60–72 cm |
| 26″ | 11–14 years+ | 5’0″+ | 145 cm+ | 28″+ | 72 cm+ |
This gives you a good ballpark reference, but geometry can differ between brands, so it’s always worth checking the specific model chart for the best fit.
What to Do if Your Child Is in Between Kids’ Bike Sizes
If your child sits between two sizes, consider:
- Growth: Sizing up can extend use, but only if they can touch the ground and reach the brakes.
- Confidence: Smaller bikes feel easier to handle, which helps new riders.
- Adjustability: Check seatpost and handlebar range—some bikes give room to grow without losing comfort.
Pick the bike your child feels safest and most confident on today.
What If I Got My Bike Size Wrong?
Then ask your merchant, if you can send your bike back to get the right one. If you don’t want to do that, then you can do the following things:
- Move your saddle to the front or rear
- Buy a longer or shorter stem. It changes your body position
- Buy a longer seat post
Consider also: JensonUSA fitting guide
Give it time to get the feeling right. I remember when I got my first 29er mountain bike. It felt like a ship and seemed difficult to ride in narrow trails of the forest.
Frequently Asked Questions
What size push bike do I need?
Push bikes are typically sold with 10" - 14" wheels. A 10-inch push bike will usually fit kids aged 18 months to 2 years; a 12-inch push bike will fit kids aged 2-4 years; while a 14" push bike will typically fit kids aged 3-5 years old. These are just general recommendations—for the best fit, consider your child's inseam length.
What size bike do I need for my height?
To find out what size bike you need for your height, you should consult a sizing chart for the type of bike you're interested in, such as road, mountain, or hybrid. Depending on the type, bike size charts will match your height to a corresponding frame size denoted in centimeters, inches, or general sizes (XS, S, M, L, XL).
Is a 26-inch bike for adults?
A 26-inch bike can be suitable both for adults and for kids, depending on the context. Kids' 26-inch bikes are suitable for teenagers and shorter adults. However, some adult bikes, such as touring bikes, fat bikes or electric bikes, also come with 26-inch wheels, but these have larger frames and are not suitable for children.
What height is a 26-inch bike good for?
A kids' 26-inch bike (a bike with 26-inch wheels) is typically suitable for teenagers and shorter adults who are around 5'0" to 5'3" tall. However, bikes for adults with 26-inch wheels, such as fat bikes or some electric bikes, are often available in a few frame sizes and might fit adults who are 6 feet in height and taller.
How do I know if a bike is too big or too small?
A bike is considered too big if you cannot stand over the frame with both feet flat on the ground without the top tube touching your crotch, or if you have to stretch too far forward to reach the handlebars. Conversely, it's considered too small if you feel cramped when riding, can't adjust the seat high enough, or your knees hit the handlebars when pedaling.
___ Inch bike for what size person?
To determine which bike size is suitable for a particular height range, consult a specialized bike size chart for the bike type you're interested in, such as our road, mountain, and hybrid size charts above. These charts match rider heights with appropriate bike sizes, allowing you to get a proper fit.
Hi,
I’m 5’11″with an inseam of 32.5 barefoot. What size road bike would work best for me? I’ve had a Cannondale R800 56cm for years and at times it does feel a little small.
Thanks,
Tim
Hey Tim, I think you’ve answered your question. A 58cm size frame should be a much better fit. 🙂
female, trying to fit hybrid with comfort in mind, ride both on and off road *leisurely*-5’6″ w apparently freakishly long legs?; 31 inseam. what frame should i be looking at? 17″?19″? I vaguely remember during my last bike shop fit them discussing me using a mens bike for better fit?…have been riding for a while but learned a lot from your site.
Hey Anne, your legs are a bit longer than what can be considered average for your height. But I think a 17″ size hybrid bike is a good choice. Men’s and women’s bikes don’t really differ that much. Usually the saddle, stem, and handlebar are different, but you can swap these easily anyways.
Hello!
I’m a 20yr old guy. 187cm tall and with a leg inseam of around 92cm = 36 inches.
My legs are pretty long so I’m not too sure what size bike to get.
My eyes are set on one(second hand though) and the seller says the size is 26inch.
Would it be suitable? I hope it isn’t a stupid question but I am very new to this world of cycling(learnt in the past few weeks on a bike meant for bike sharing apps).
Thanks for your time 🙂
Hi Ian, if you’re planning to buy a road bike, I recommend a 58cm frame. If you’re planning to buy a MTB, I recommend a 21″ size frame with 27.5″ or 29″ wheels.
The 26″ size you mention probably refers to the wheels, which doesn’t really say much. However, if it refers to the size of the frame (which I doubt), it means that the bike is gigantic and you should pass. 🙂
Excellent article Jeff, appreciate the effort. Just getting back to cycling after five years in the Middle East and online shopping is clearly the only choice given the state of the world right now. Need a bike again!!!!
I’m happy you find it useful, Steve! The current situation is less than ideal for bike shopping, but we should try to make the best of it. Have fun cycling again!
Hi
Want to buy this bike https://www.ghost-bikes.com/en/bikes/fully/bike/sl-amr-29-al-u
SL AMR 2.9 AL U GHOST FULLY
I am 186 cm but my inseam is 82cm,arms 63-64 cm
Is better M or L version of bike for me?
Hey Mexx, you should definitely get the Large (L) size. 🙂
Hello Jeff. As of now I am really stressed out. Unfortunately I am one of those people that is between sizes, I would say I am about 6’1 and have a 32in(82cm). I bought a cervelo c3 on 58cm an endurance bike which is supposed to be comfortable. I have never been somewhat comfortable on it. The top tube almost hits my crotch when.
Because of this I this I decided to buy a 56 specialized Roubaix, or a trek Emonda, and salesmen tell me to get a 58, because of my height. I am not sure if cervelos run larger than other sizes. Hope you can help me out.
Thanks!
Hi Jose, a 58cm size frame should be a good fit for you. However, your inseam length seems a bit short for your height, perhaps that’s the problem? That would mean your torso is longer than average which would affect the fit.
Both Cervelo C3 and Specialized Roubaix have detailed geometry charts available. I recommend opening both and comparing the reach and standover height to see whether or not a 56cm Roubaix would make a difference.
Good luck!
Silly question from newbie – is it ever going to work if you buy a bike with standover length slightly longer than cyclists inseam measured with shoes on? Would highly appreciate your kind response.
It can work if you don’t mind standing on your tippy-toes when you straddle the bike. 🙂 It’s definitely not recommended and not comfortable and you also run the risk of hurting yourself.
Hey Jeff,
Such a wonderful resource for people during COVID-19 when shops are shut. I’ve scanned through your comments to see if I could get any pointers on my height/inseam and appropriate bike size, but thought I would ask to be safe as it is such an investment to get a bike and couldn’t find a good comparable for a road bike!
I am 177cm tall and have an 80.5cm inseam (both barefoot). From fingertip to fingertip (ape index) I am just under 173cm.
I am going for a Specialized Allez E5 Elite 2020 Road Bike. I think I am exactly between a 54″ frame and 56″ frame and am really struggling to pick the best option. I am pretty comfortable on road bikes and recall sizing being an issue last time around, however, I can’t for the life of me remember what size frame I purchased last and it has been some years since I last rode due to an accident.
Many thanks in advance!!
https://www.evanscycles.com/specialized-allez-e5-elite-2020-road-bike-EV366597
Hi Ally, I think a 54cm would work well for you considering your arm span is quite a bit shorter than your height. Whichever size you end up choosing, you can make it work with small adjustments if you’re not 100% satisfied with the fit. 🙂
Hi Jeff,
I recently got a road bike that hurts my backside when I ride for more than about 5 minutes.
I’ve been told that it may be a number of things, that the bike may be too big for me or that it’s because I haven’t ridden properly in over a decade.
Any idea what it could be? I understand there are adjustments and accessories to help but surely they should only be needed to get you from one hour of comfort to two and not to help 5 mins?
Do I just need to push on through?
Thanks
Hey Danny, as you’ve been told, it could be a number of things, so it’s very hard for me to give you advice without knowing more details. Some of the most probable reasons are wrong bike size, poor fit, or poor flexibility.
If possible, I’d advise visiting a local bike shop or a bike fitter and checking whether or not the bike fits you. Improving your flexibility and mobility won’t hurt either. Definitely don’t push through it, though, pain is always our body’s way of telling us something important.
Good luck!
Hi! I’ve recently thought about buying a bike for fun and for exercise as well and was thinking a hybrid would be best for my purpose. I’m not looking to spend more than maybe $300-$400 at the most and I’ve read some of your articles on the best bikes in each category. I’m nervous to order online because of sizing and I’ve been looking on Craigslist and Facebook Marketplace as well. Depending on the bike, it looks like I’m always right on the cusp of two sizes and I’m not sure which way to err. I’m a woman who is 5 feet 5 inches tall and my inseam is 30 inches. Can I use just these two measurements and get a good fit? Thank you for any help!!!
Hi Angie, your inseam length is pretty much average for your height, so I don’t think you’d make a mistake going either way. If I had to choose, I’d recommend going for the smaller size when in doubt as it is easier to get the right fit.