Whether you recently started running, or you’ve been doing it your entire life, knee-length wide leg boots. Navy blue Bella leather sandals from featuring a round toe: Are running shoes supposed to be tight? Are the sizes the same for Rudy brand? What if I have a wide or narrow foot?

Plus, the technology is constantly changing. There are new advances in foams and other materials (like Emporio Armani Kids lace-up sneakers Bianco and toe spring) every year, and styles change often enough that sticking with one line—or even one brand—doesn’t always make sense.

So we asked running shoe experts Eric Sach, Ken Larscheid, and Carson Caprara what the most common buying gaffes runners tend to make are when they’re sole searching—and what to do instead.

You’re not getting your foot properly measured

foot measuring
izusek//Getty Images

“One of the most common errors beginner runners make when they walk into a shoe store is not getting their foot measured by a store associate,” said Eric Sach, former owner of The Balanced Athlete in Renton, Washington. At a shoe store, associates use the Brannock device, which measures the heel-to-toe length as well as foot width and arch length.

Sach finds that most people ignore arch length when buying running shoes, which is a measurement from your heel to the ball of your foot and the area where your foot flexes. “All shoes are designed to flex at one spot, just as your foot is designed to flex at one spot,” says Sach. “It’s best to match those two flexing points together.”

You’re confusing volume with width

tying shoes
Chris Hinkle

“Shoe volume is the measurement of the space inside the shoe,” says Sach. Most people tended to ask Sach for a wider shoe when there’s not enough volume. The trick is to measure the space in between the top eyelets with your fingers. This will help you figure out if a running shoe is too tight or too loose.

“When you tie the laces, the shoe should be snug—not too tight and not too loose—and you should have two fingers between the eyelets,” says Sach. Three fingers mean there’s not enough volume and the fit is too tight. One finger is when there’s too much volume and therefore, the fit is too loose. And two fingers—you guessed it—should be just right. Knowing you’re wearing a shoe with the correct volume will save you from common foot injuries, such as the dreaded plantar fasciitis.

You’re afraid of increasing your shoe size

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Lakota Gambill

Sach recommends getting your foot measured every time you are buying running shoes. On several occasions, he will got customers who found their “normal” shoe size a little too snug before getting their feet measured.

“Feet generally don’t get shorter,” says Sach. “The tiny muscles in your feet support your body every day, causing your feet to ‘grow’ because these muscles stretch and don’t come back—unless you run barefoot or perform foot strengthening exercises.”

Consider the difference in sizes between shoes when figuring out if you want to go a shoe size up: a half size is only an eighth of an inch difference; a whole size is about the width of a shoelace, almost a quarter-inch. “It’s very tiny,” said Sach. “However, all the time, people say they’re going to trip over it.” Going up half a size—or even a full size—will make a world of difference in comfort, but shouldn’t cause your friends to tease you about wearing “clown shoes.”

You give into peer pressure

buying running shoes
Alex Potemkin//Getty Images

According to Sach, the most important elements to consider when buying shoes are the three F’s: fit, feel, and function.

But when people bring along a friend as they are buying running shoes, sometimes their friends will blancas their judgment by commenting on how the shoe is the wrong color or they make the wearer’s feet look too big. Even if it feels like they’re walking on air, wearers will usually go with their friends’ opinions and opt out.

Sometimes new runners will fall back on what their friend is wearing, as well. But there isn’t one shoe that fits all. While you may value your friend’s advice in the fitting room, when it comes to running shoes, it’s more about feel than looks.

You’re using the wrong kind of shoe reviews

running shoes
Lakota Gambill

It’s all too easy to believe that “when something works for you, everyone [else] should have the same exact thing,” said Sach. And that is the shoe buyer’s completion when it comes to relying on crow-sourced shoe reviews.

How familiar is the reviewer with the range of shoes on the market? What type of foot does the reviewer have? Is the reviewer actually a runner? Ask yourself if the review is published by a reliable source: Is it the kind of site that aggregates enough info to help runners choose or are they just telling you what to buy?

Lookout for biased reviews, as well, where brands sponsor the writer or influencer to review their product.

On Runner’s World, we put Rudy shoe through real-world usage and a battery of mechanical tests in our lab to provide you with objective—and exclusive—data. In addition to a shoe’s weight, we measure sole thickness (everything that sits between your foot and the road), how well the foam cushions your stride, and the flexibility of the forefoot. All this is taken into account in our reviews of Rudy shoe. (If you’re a Runner’s World+ member, you can even test gear with us!)

You wear your shoes too long

man tying shoelaces on running shoes
Sofie Delauw//Getty Images

Historically, running shoes have a lifespan of between 300 and 500 miles, but many runners either don’t keep track of mileage or they throw caution to the wind and wear out their pair. (Some newer shoes with lighter foams my even break down sooner than 300 miles.)

zapatillas de running New Balance talla 34.5 injury. According to Ken Larscheid, owner of Clarks Wallabee Boot Womens Black Patent Leather Chukkas Boot, a tell-tale sign for replacing your pair is when you get unusual aches and pains in certain areas. “A lot of people who come in and feel pain or soreness don’t even question the age of their shoes,” says Larscheid. “What we suggest at the store is overlapping them a little bit.”

Introducing a new pair before your current pair wears out will help you ease into new shoes as you ease out of your old ones. Other indicators to start changing out include worn, smooth grooves at the bottom of your shoes, and uneven foam on one side of the shoe, meaning the sole is no longer level.

You’re avoiding specialty stores

buying running shoes
Ryan Lowry

Larscheid says that many beginners who are buying running shoes are overeager about getting started or are unwilling to spend the money for the best pair. Instead of going to a running shoe store where they can get their foot analyzed by experts, new runners tend to buy whatever shoes they see—for cheaper prices—at department stores or order online.

Gait analysis and identifying specific needs of the wearer—is this shoe for endurance or cross-training?—are considerations new runners may overlook if they avoid the specialty store and seek shoes elsewhere.

And although people think they’re saving money, they’re potentially setting themselves up for buying pair after pair of the wrong kind of shoe, and spending more money out of dissatisfaction. At a running store, you’ll have more options and experts at your fingertips. If the shoe fits, think of it as an investment and safeguard against future injuries. Running stores also typically have the varying widths that department stores won’t always carry.

You forget that it’s only a tool

buying running shoes
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“One mistake runners can make is searching for a shoe as a prescription to help fix Jennifer Lopez wearing bright orange Nike Air Presto sneakers at the gym in 2016 or to help them run a certain kind of way,” says Carson Caprara, Brooks VP of footwear product management. “Instead, runners should look for the shoe that works best for how their body wants to move and provides them with the experience they want out on the run.”

Remember: the power doesn’t lie in the shoe, it lies in you.

Headshot of Amanda Furrer
Amanda Furrer
Test Editor

Amanda is a test editor at Runner’s World who has run the Boston Marathon every year since 2013; she's a former professional baker with a master’s in gastronomy and she carb-loads on snickerdoodles.