How to Choose a Bathing Suit for Girls | Fit That Lasts All Summer

Choose a girls’ bathing suit by measuring the chest, waist, and hips, then matching those numbers to that brand’s own size chart.

Picking a swimsuit for a girl usually goes sideways at one moment: holding up a suit and guessing. A size 10 from one brand runs completely different from a size 10 at another, and the child who wears a solid medium in tops might need a large in swimwear. The way to choose a bathing suit for girls that actually fits starts with a cloth tape measure, three body measurements, and the exact size chart from the brand you’re buying.

Measure The Body, Not The Age

Age labels are a starting point, never a finish line. Brand sizing varies so much that relying on “she’s 8, so size 8” produces a suit that’s either digging into shoulders or slipping off during a dive. Take these three measurements instead:

• Chest: wrap the tape around the fullest part, keeping it level across the back.
• Waist: Nike’s girls’ swimwear size chart directs you to measure the narrowest part of the body, keeping the tape horizontal.
• Hips: measure around the fullest part of the seat, tape parallel to the floor.

For one-piece suits, add a torso length measurement — from the top of the shoulder, through the legs, and back up to the start point. This dimension decides whether a one-piece rides up or binds at the shoulder.

Those three or four numbers give you a column to match against the chart. If your numbers fall between two sizes on the chart, order up for growing room and order down for competitive swimming where a snug fit matters more.

Match Your Numbers To The Brand’s Chart

The same child can wear a different size at Nike, Speedo, and Zoggs — that’s normal. Each brand builds suits on different blocks, so the chart from the specific brand you’re buying wins over any general guide.

Nike publishes a dedicated girls’ swimwear size guide on its size-fit page that works from waist measurements plus age ranges. Speedo’s official kids’ chart lists age, chest, height, hips, and waist together, which makes it easy to confirm a fit across two or three dimensions at once. Zoggs recommends measuring the chest, waist, and hips the same way, and its kids’ sizing ties those numbers to both age and height.

That’s also where regional traps hide. Zoggs’ guide explicitly maps UK/AU, DE/NL, and FR conversions, so a suit bought from a European site won’t arrive in an unexpected size if you check the conversion table first.

Avoid The Three Common Fit Mistakes

Mistake one: using women’s sizing for a girl’s suit. Nike, Speedo, and Zoggs each publish separate girls’ charts that run smaller and fit differently than their adult women’s lines. A suit cut for a grown torso sits wrong on a child’s frame, with baggy shoulders and loose leg openings.

Mistake two: skipping the torso measurement on one-pieces. Girls’ bodies vary in torso length just like adults’, and that measurement catches the difference between two girls with the same chest and waist numbers. A short-torsoed girl in a long-torso suit gets a bunch of fabric at the hips; a long-torsoed girl in a short-torso suit fights straps that won’t stay up.

Mistake three: choosing loose for comfort. Swimwear needs to stay secure during water play, and a baggy suit drags, gapes, and chafes once wet. Compare your measurements against the intended product line — a training suit fits snugger than a beach suit on purpose.

Check For UPF, Then Buy With Confidence

If sun protection is a priority, only trust a UPF claim that the manufacturer states directly on the suit or its product page. The sizing charts themselves don’t rate sun protection, so a suit’s fit and its UPF rating are separate checks — confirm both before you order.

Once you’ve verified the measurements against the brand chart and confirmed the coverage, you’re ready to compare actual options. Our tested roundup of the best bathing suits for girls this season breaks down the top picks by fit, coverage, and sun protection.

Take the child’s measurements fresh each season — growth spurts rewrite the chart. Measure, match the brand’s own numbers, and the suit will last the summer without a single mid-lap adjustment.