Girls between 6 and 14 grow at varying speeds, and almost never proportionally. Length outpaces width. Then width catches up. A kid who was a size 8 at the start of term can be a size 10 by mid-term. Here is how to size girls activewear when she is growing fast, so you are not replacing it every six weeks.
Measure Her Now, Not Last Season
The single biggest mistake is buying the same size as last time without checking. Girls' bodies change unevenly. The rise can grow before the inseam. A nine-year-old can add 10cm of leg length in a single growth spurt.
Before ordering, take three measurements:
- Waist, at the narrowest point
- Hips, at the fullest point
- Inseam, from the crotch to the ankle
Compare those numbers to the size chart for the specific brand, not a generic AU size guide. Brand sizing varies more than most people expect. A Bloch size 10 fits differently to a Capezio size 10. Always check the chart before adding to cart.
If she sits between two sizes, and she is mid-growth-spurt, go up. Activewear that is slightly generous through the hips is wearable. Activewear that cuts across the waist is not.
How Much Growing Room Is Actually Useful
There is a difference between buying for growth and buying something that will not stay up during class. A size too large in a leotard means straps falling off shoulders and a sagging seat. That is a performance and confidence issue, not just a fit issue.
For leggings and shorts, one size up usually works well. The waistband elastic does most of the holding, and an extra centimetre through the leg is rarely noticeable in movement.
For fitted crop tops and bra tops, sizing up only works if the band still sits firm. If the ribcage measurement puts her at the top of a size, go up. If she is in the middle of a size, stay there. A loose band provides no support through jumps or gymnastics conditioning.
Knowing how to choose the right activewear for dance, gym and sports before you buy helps you avoid the most common sizing errors from the start.
Fabrics That Handle Growth Better
Stretch percentage matters. Look for activewear with at least 15 to 20 percent elastane or spandex content. That level of stretch accommodates a wider range of body sizes without the garment losing its shape after washing.
Four-way stretch fabric moves with the body in every direction. This is important for dance and gymnastics, where the range of movement is larger than most sports. A fabric that only stretches in one direction will restrict movement and wear out faster at the seams.
Moisture-wicking polyester and nylon blends tend to hold their shape longer than cotton-heavy fabrics. Cotton stretches out with wear and does not recover as well. For active use several times a week, that matters.
If you are buying for a child who is particularly hard on her gear, it is also worth reading about how to wash girls activewear so it lasts longer. The right wash routine can add months to a garment's life, even through a growth spurt year.
Waistbands, Seams and Practical Fit Details
Waistbands
A wide, flat waistband distributes pressure across the body. Narrow elastic waistbands can dig in as she grows, especially across the belly. Look for waistbands that fold over or sit flat against the skin without rolling.
Flatlock Seams
Flatlock stitching lies flat against the skin and does not rub. For girls who are sensitive to texture, this is worth checking before buying. It also holds up better through repeated wash cycles, which matters when you are buying for a child who trains three or four times a week.
Gussets and Panelling
A gusseted crotch seam gives extra room through the hips without adding bulk to the waistband. For girls who are growing through the hips faster than the waist, this construction detail makes a genuine difference to comfort and fit longevity.
When to Replace, Not Resize
Some signs tell you a garment is done, regardless of size. Pilling across the thighs means the fabric is breaking down. Waistband that no longer recovers after washing means the elastic is spent. Fabric that has gone sheer through the seat means it has been worn and washed past its useful life.
Sustainable choices matter here too. Before replacing everything at once, check whether the items showing wear are worth swapping for better quality next time. There is useful guidance on what to actually look for in eco-friendly girls activewear if longevity and materials are a priority for your family.
Browse our girls activewear for dance, gym and sports, where every product listing includes a detailed size chart. If you are unsure between sizes, the team can help you find the right fit before you order.
