Do Sneaker Sizes Vary by Brand? A Fitting Guide

Yes, sneaker sizes vary by brand

Sneaker sizes do vary by brand, sometimes by as much as a half size or more. Nike, adidas, New Balance, and ASICS each use their own lasts, the three-dimensional forms around which a shoe is built. A last determines not just length but also the shape of the toe box, the height of the instep, and the width across the ball of the foot. Two shoes that both say "US 10" can fit very differently because their lasts are not the same.

The practical consequence is that your size in one brand is only a starting point for another. You cannot assume that a US 10 in a running shoe from one maker will feel the same as a US 10 in a lifestyle sneaker from a different maker. The reliable way to buy is to measure your feet, then use each brand's published size chart as the reference for that specific purchase.

Why brands fit differently

Every sneaker brand designs its products for a particular audience and purpose. A running shoe company like ASICS builds many of its models on lasts that allow for toe splay and a secure heel hold, because those features matter for runners. A lifestyle brand may use a last with a more tapered toe for a sleeker look, even if that means less room for the toes.

The last is the single biggest factor in how a shoe fits. It sets the internal length, the width at the ball of the foot, the arch height, and the toe box shape. Brands rarely share lasts between each other, and they often change lasts within their own lineup based on the shoe's intended use. That is why a brand's size chart can be accurate for one model and misleading for another. For a deeper look at how last shape affects fit, see our guide to sneaker last shape.

Nike, adidas, New Balance, and ASICS compared

While no two brands share a single sizing standard, some general patterns can help you start from the right place.

Nike tends to run narrow through the midfoot and heel, with a snug fit that many wearers describe as true to length. If you have a wider foot, you may need to go up half a size or choose a style that uses a stretchy knit upper. adidas sizing is generally comparable to Nike in length, but the fit across the toe box varies more between models: the classic Samba fits differently from the Ultraboost, for example.

New Balance is known for offering width options on many models, including narrow, standard, wide, and extra wide. That makes it a strong first stop if your feet are wider than average. ASICS also offers wide versions of many running shoes, and its standard width tends to be a comfortable, roomy D for men and B for women. For the best results, look at our best ASICS sneakers and best New Balance sneakers guides, which note the width options for each pick.

Start with your measured foot length

Before you compare sizes across brands, measure both feet. Foot length changes with age, weight, and even the time of day, so a measurement from a few years ago may no longer be accurate. Use a ruler and a wall, or a Brannock device at a shoe store, and measure from the back of your heel to the tip of your longest toe. Do this in the evening, because feet spread slightly through the day.

Write down the measurement for each foot in inches or centimeters. Use the longer foot as your reference for size, since shoes need to fit both feet. For a step-by-step walkthrough, see our article on how to measure foot size.

Use each brand's own size chart

Once you have your foot length in centimeters, go to the brand's official size chart for the specific model you want. Brands publish charts that map foot length to US, UK, and EU sizes, and these charts are the most reliable conversion tool you have. Do not rely on a general "size converter" you find elsewhere, because it cannot account for brand-specific lasts.

If a chart puts you between sizes, choose the larger size for most sneaker types. A shoe that is slightly long can be managed with a thicker sock or a heel lock lacing technique, but a shoe that is too short will cause blisters and toe damage. For a fuller explanation of how to read size charts, see our sneaker size conversion article.

Width options change the fit more than length

Length gets most of the attention, but width is often the difference between a comfortable shoe and one you cannot wear. If your feet are wide, a shoe built on a narrow last will feel tight across the ball of your foot even when the length is correct. Brands handle this differently: New Balance and ASICS offer explicit width sizes on many models, while Nike and adidas mostly offer standard width only, relying on the upper material to stretch.

Before you buy, measure the width of your foot at the widest point, just behind the toes. Then check whether the model you want comes in a wide option. For guidance on how to interpret those measurements, read shoe width explained and wide feet sneaker fit marks.

The model matters as much as the brand

A common mistake is to think that your Nike size transfers to every Nike shoe. In reality, different models within the same brand can fit differently because they use different lasts. A basketball shoe with extra padding around the ankle will feel more snug than a minimalist running shoe of the same labeled size. A leather upper will stretch less than a knit one, so the same size can feel tighter.

The upper material also plays a role. Knit and mesh uppers adapt to your foot shape over time, while leather and synthetic leather hold their shape more firmly. If you are choosing between a leather sneaker and a knit one, expect the leather version to feel more structured at first. See our article on how sneakers should fit for a checklist you can apply to any pair.

How to convert sizes between brands safely

When you move from one brand to another, use your foot length in centimeters as the anchor. Look up the size chart for the new brand and find the size that matches your measured length. Start with that size, then use what you know about the brand's fit tendencies to adjust. If the brand tends to run narrow and your feet are wide, go up half a size or look for a wide option.

If you are buying online and the store offers free returns, order two sizes when you are between sizes or unsure about the fit. Trying both at home is faster and cheaper than a round of exchanges. Check the model's reviews for fit notes from other buyers, but weigh those against your own measurements rather than treating them as rules.

What to pick for your use

Questions

Should I buy the same size in Nike and adidas?

Usually, but not always. Nike and adidas sizes are broadly similar in length, but the fit across the midfoot and toe box differs between models. Check the specific model's size chart and read its fit notes before buying.

Do New Balance shoes run big or small?

New Balance standard width is often described as roomy compared to Nike, especially in lifestyle models. Because New Balance offers width options, the labeled length can fit differently depending on the width you choose.

Are ASICS sneakers true to size?

Most ASICS running shoes are true to length and offer a comfortable standard width. If you have a narrow foot, you may prefer a model with a snugger heel or a lacing adjustment to lock the foot in place.

My foot measures between two sizes. Which should I pick?

Choose the larger size. A slightly long shoe can be managed with a thicker sock or heel lock lacing, but a short shoe will cause discomfort and potential toe injury. This advice applies across all brands.

Is it better to go up half a size for wide feet?

Not necessarily. Going up in length adds room along the foot, but it does not add width in the right place. A wide version of the correct length is usually a better fit than a longer version of the standard width.