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, measure her current waist, hips, and inside leg. Compare those numbers to the brand's size chart, not to a general age guide.
Different brands size differently. A size 10 in one label can be a full size out from another. Always go back to the measurements, every time.
What to look for in activewear that keeps up with growth
Fabric and cut matter as much as the size label. Pieces that stretch in four directions, move with the body, and recover their shape after washing will last longer through a growth phase than rigid or structured styles.
- Look for a wide, flat waistband. It sits lower on the hips if she grows through the waist, and does not dig in.
- Full-length tights with a fold-over waist can be worn scrunched or full-length, buying several months of extra wear.
- Shorts and bike pants in a longer cut give room as the hips widen, and still look neat if worn with a longer top.
- Racerback tanks with a looser arm opening accommodate a broadening upper body without pulling across the chest.
If you are buying online, check the inseam measurement in centimetres, not just the age range. Age ranges are a starting point only.
Sizing up versus buying to fit right now
This is the practical question every dance parent faces. Buying a size up saves money if she is mid-growth-spurt, but oversized activewear in dance or gymnastics can be a real problem. A waistband that rolls, shorts that shift during a cartwheel, or tights that bunch at the knee affect how she moves and can knock her confidence.
A better approach is to buy true to her current measurements for structured pieces like unitards or fitted shorts, and size up by one for basics like tights and training tanks where fit is more forgiving. Check our range of girls activewear for dance, gym and sport and use the size charts listed on each product page as your guide.
If she is between sizes, go up for bottoms and true to size for tops. A slightly longer top is less disruptive to movement than a waistband that will not stay up.
Fabrics that are worth the investment during a growth phase
Cheaper fabrics lose their shape faster, which means pilling and sagging well before she has actually outgrown the piece. Nylon and spandex blends generally hold their shape and colour through repeated washing far better than polyester-only options. If she is active several days a week, that matters.
Moisture-wicking fabrics also stay comfortable through long training sessions and are worth prioritising for any child doing more than one activity. If you want to know what else to look for in quality girls activewear, including fibres and certifications worth checking, this guide to sustainable girls activewear and what to actually look for is worth reading before you buy.
And once you have found pieces she loves, how you wash them determines how long they last. Heat and harsh detergents break down stretch fibres quickly. This practical guide on washing girls activewear so it survives the growth spurts covers exactly what to do and what to avoid.
A practical sizing checklist before you order
- Measure waist, hips, and inside leg in centimetres today.
- Compare to the brand's own size chart, not an age guide.
- Check the inseam measurement listed in the product details.
- Size up for tights and tanks, true to size for fitted shorts and unitards.
- If between sizes on bottoms, go up.
- Prioritise four-way stretch and a recoverable fabric if she is in a fast-growth phase.
Browse the full girls activewear collection and check the size charts on each product page. If you are unsure between two sizes, get in touch and we can help you work it out.
