How to Pick the Right Size and Fit for Women’s Workout Gear | Measure First

Correct sizing starts with a bra-free tape measurement of band, bust, waist, and hip, then a check of the brand’s own chart — because a medium in one label is a large in another.

A sports bra that rides up, a legging that gaps at the waist, a top that binds across the shoulders — every one of those problems traces back to a size picked by habit instead of by tape. Apparel sizing is not standardized across brands, garments, or even cuts within one brand, so the only reliable method is to measure your own body now, compare against that specific manufacturer’s current chart, and then move in the garment before you commit.

This guide covers the measurements that matter, how to read a size chart without falling into the common traps, and the in-motion checks that separate a garment that fits from one that merely buttons up.

Take Your Measurements Before You Open the Size Chart

Four numbers cover almost every piece of workout gear: underbust, bust, natural waist, and fullest hip. Take them over bare skin or a thin unpadded layer, with the tape level and snug — not tight.

• Underbust (band): wrap the tape directly below the breasts, level around the rib cage, and keep it snug enough to stay put without pressing in. If you’re measuring for a sports bra, wear an unlined, unpadded bra that holds the breasts in their natural shape rather than a compressive or push-up style.
• Bust: measure around the fullest point, tape parallel to the floor and level across the back. It should sit flat against the body without restricting a normal breath.
• Natural waist: the narrowest point of the torso, usually just above the navel. Don’t suck in.
• Fullest hip: around the widest part of the seat, feet together.

Write the numbers down. Tape-measure memory is worse than it feels, and you’ll want them again for the next brand.

Read the Brand’s Chart, Not a Universal Size

REI states plainly that sports bra sizing is inconsistent across brands and recommends trying multiple brands, sizes, and styles — and that warning applies to leggings, tops, and shorts too. A brand’s chart is the only sizing document that applies to that brand’s garment.

Two things commonly trip people up when reading charts:

• Rounding rules differ. One brand tells you to round the band up, another down. Follow the instructions on the chart you’re using rather than carrying over a method from somewhere else.
• Some brands run parallel fit lines. A standard chart and a Contour Fit chart, for example, are not interchangeable — Contour Fit uses a narrower waist relative to hip. Check which chart the specific product page points to.

For band-and-cup sizing, subtract the band measurement from the bust measurement. If you’ve been buying the same bra size since high school, that range is worth checking.

Check the Fit in Motion, Not in the Mirror

A garment that looks right standing still can fail on the first stride. Before you accept a fit — and ideally before you cut the tags — move through the activity you bought it for.

For a sports bra, Nike recommends five jumping jacks as a bounce test. Excessive movement means you need more support, wider straps, or a different back design. The band should sit level around the torso and stay in place when you raise your arms, with room for about two fingers between band and body. Straps should allow two fingers between strap and shoulder without digging in or sliding off. Cups should hold all breast tissue without gaping, overflow, wrinkling, or bulging at the sides. If the bra has underwire, it should rest on the breastbone at the front and against the ribs near the armpit — never on breast tissue.

For bottoms, do a squat and a high knee. A waistband that rolls down or gaps at the back during either movement is the wrong size or the wrong rise for your build. For tops, reach both arms overhead — if the hem rides up past the waistband, size up or look for a longer cut.

Match support level to the activity itself. Running and repeated jumping generally call for a more secure construction than yoga or cycling, and the manufacturer’s own support rating on the product page is the number to trust. Compression alone does not equal adequate support.

Where Most Sizing Mistakes Happen

The same five errors account for most bad-fit returns.

• Buying the same nominal size across brands without checking each current chart. A medium is a suggestion, not a specification.
• Measuring over a padded or heavily compressive bra, which inflates the bust and skews the cup size.
• Letting the tape slope, pull tight, or sit on the breast tissue — all three produce a number that isn’t your measurement.
• Sizing up the band to fix cup overflow. The right move is a larger cup or a different style, not a looser band.
• Tightening the straps to fix a loose band. If the band rides up in back, the band is too large, and no amount of strap adjustment will hold it down.

When you’re shopping for a gift rather than for yourself, the same rules apply but the measuring is harder — sizing up in a style with adjustable closures is the safer play, and a roundup of tested workout gifts for her cuts down on guesswork. If you’re ordering online and the brand offers both, order two sizes and return one; the shipping cost is usually smaller than the cost of a garment you never wear.

The sizing charts that govern all of this are published by the brands themselves. Nike’s women’s sports bra size and fit guide is a good example of how detailed a current chart gets, listing band and cup combinations rather than a single letter.