How to Measure Yourself and Use an Athletic Wear Size Chart

Athletic wear that fits well moves with you, supports your activity, and stays in place. Sizing varies considerably across manufacturers, so a medium from one label may fit like a large from another. The only reliable way to shop is to start with your own measurements and then read each brand's size chart directly.

What You Need Before You Start

A flexible fabric tape measure is the right tool for this. Rigid metal tape measures curve awkwardly around the body and produce inaccurate readings. Fabric tape measures cost very little and are available at fabric stores, pharmacies, and online.

Wear fitted underwear or a thin base layer while measuring, not heavy clothing that adds bulk. Stand naturally, breathe normally, and do not suck in or push out. Have someone help you if possible, especially for back measurements, since reaching around yourself tends to shift the tape out of position.

Taking Your Three Core Measurements

For athletic wear, chest, waist, and hips are the measurements that matter most. Here is how to take each one accurately.

Chest. Wrap the tape around the fullest part of your chest, typically across the nipple line. The tape should be level across your back and snug against the skin without pulling. Read the number where the tape overlaps at the front.

Waist. Find your natural waist by bending sideways. The crease that forms marks the narrowest part of your torso, usually an inch or two above the navel. Wrap the tape around that point, keeping it parallel to the floor. For athletic bottoms specifically, some brands also list the waist in terms of the garment's relaxed, unstretched opening, which matters when a waistband does not adjust.

Hips. Stand with your feet together. Wrap the tape around the widest part of your hips and seat, which is usually 7 to 9 inches below the natural waist. Keep the tape level and snug but not tight enough to compress the skin.

Write all three numbers down in inches, since most US size charts use inches. If your tape measure only shows centimeters, divide by 2.54 to convert.

Reading a US Athletic Wear Size Chart

Most US athletic brands list sizes as XS, S, M, L, XL, and sometimes XXL or beyond. Each size corresponds to a range of body measurements, not a single number. A medium, for example, might cover a chest of 35 to 37 inches. If your chest measures 36 inches, you fall in the middle of that range and the size is likely to fit well.

Size charts are usually organized as a table with rows for each size and columns for chest, waist, and hips. Read across the row for a size to see whether all three of your measurements land within the listed ranges. When they do not all land in the same row, decide which measurement to prioritize based on the garment type.

• For tops and sports bras, prioritize your chest measurement.
• For leggings and shorts, prioritize your hips, then check the waist range.
• For jackets and hoodies, prioritize the chest and consider whether you plan to layer underneath.

When Your Measurements Fall Between Sizes

This is common, and the right choice depends on the garment's intended fit. Athletic wear generally falls into two categories: compression fit and relaxed fit.

Compression garments, like running tights and fitted base layers, are designed to sit close to the body. If you are between sizes in a compression item, size down if you want a secure, performance-oriented feel. Size up if ease of movement is your priority.

Relaxed fit pieces, like training shorts or pullover hoodies, have more built-in ease. Sizing up is usually the safer choice here, since these garments are not meant to be form-fitting in the first place.

Also check whether the product page mentions the model's height and the size they are wearing. This gives you a practical reference point that a number on a chart cannot fully convey.

Accounting for Fabric and Stretch

The fiber content and construction of a garment affect how it fits in practice. Four-way stretch fabrics, common in yoga and training wear, expand significantly in all directions. A garment made from a high-stretch fabric may fit well even if your measurements sit near the top of a size range. Woven fabrics with little stretch, used in some training shorts and wind jackets, offer minimal give, so precise measurement matching matters more.

Check the product's listed fabric composition when it is available. A fabric described as containing elastane or spandex will have considerably more stretch than one made purely of woven nylon or polyester. When in doubt about stretch, note the return policy before purchasing, since fit is ultimately confirmed by wearing the garment through a range of motion.

Re-measure yourself periodically if your body changes, since size charts are only as useful as the measurements you bring to them. Keeping a small card with your current chest, waist, and hip measurements makes it easy to check any size chart quickly whenever you shop.