How to Choose the Right Size Leggings for Kids? | Measure, Then Match

Choosing the right size leggings for kids comes down to body measurements, not age. A child’s height and waist measurement will always beat the number on the tag, because every brand builds its own fit. Skipping the tape measure is the single biggest reason parents end up with leggings that sag at the knees or pinch at the waist.

Why Age-Based Sizing Fails

Children grow at wildly different rates. Two seven-year-olds can easily be a full size apart in both height and waist, so a label that says “7-8” tells you almost nothing about how a specific pair will fit.

Nike’s kids clothing chart lists numeric sizes (8–9, 10–12, 14–16) that map to height, chest, waist, and hip ranges in inches, not age brackets. Under Armour’s girls’ bottoms guide follows the same logic, giving body ranges rather than birthday cutoffs.

How to Measure a Child for Leggings

Grab a soft tape measure and have the child stand straight in light clothing. You need three numbers, and only three.

• Natural waist: the narrowest part of the torso, usually right above the belly button. Keep the tape horizontal and snug, not tight.
• Hips: the fullest part of the seat, with the tape held level all the way around.
• Height: measured against a wall with shoes off.

Adidas instructs parents to measure chest, waist, and hips horizontally, plus inseam and height vertically. For leggings specifically, the waist and hip numbers do the heavy lifting—a child who falls in one size for waist but another for hips should size up to the larger measurement, since leggings stretch less than loose pants.

Matching Measurements to a Brand’s Chart

Once you have the numbers, open the size chart for the exact brand you’re buying. Under Armour’s girls’ bottoms chart is a dedicated guide for pants and leggings, which makes it a reliable reference when their products are on the list.

Official charts from Nike and Adidas follow the same principle but draw the lines differently. A child measuring a 23-inch waist might land in a Nike 10–12 but an Adidas 11–12, and both would be correct for their own garments. That’s why swapping charts across brands is a trap: the label looks similar, but the fit rarely matches.

If your child lands between sizes on a brand’s chart, check that brand’s fit notes. Most official product pages will tell you whether a style runs snug (typical for compression-style leggings) or true to size, which is the difference between a comfortable week of wear and a return trip.

For product-specific advice, the most compatible source is always the leggings page from the brand you’re actually purchasing. Those pages reflect the current cut of that specific garment, which a general chart cannot guarantee. If you’re comparing several brands at once, our tested roundup of children’s leggings for active kids shows how the leading options fit across different body types.

Common Size Mistakes Parents Make

• Trusting the age range on the tag. Age is a starting point for shopping, not a fit tool. Use it to narrow the rack, then confirm with measurements.
• Measuring over bulky clothes. A winter base layer or thick jeans adds an inch or more of false girth. Measure directly over the body or thin underwear.
• Mixing size systems. A “large” in Nike’s kids range and a “large” in Under Armour’s girls’ range are different garments. Each brand’s chart is only valid for its own products.

Leggings should sit at the natural waist without digging in. If the waistband rolls down or leaves red marks, that size is too small even if the chart says it fits—comfort beats the printed numbers every time.