Swimming guide
Kids Swimsuit Size Chart
Measure chest, waist, and hips, then use the exact suit chart. See an official Speedo girls' chart and movement-based fit checks.
Short answer
Photo: Brian Matangelo / Unsplash
Age is a cross-reference on some kids' swimsuit charts, not the measurement. Speedo's current sizing instructions use chest, waist, and hips for standard swimwear and tell shoppers to measure with a soft tape held flush rather than tight.
Fit expectations also depend on the product. Speedo describes recreational swimwear as close-fitting with freedom of movement, training swimwear as snug and supportive, and racing products as a separate compression system. Use the activity and chart for the exact suit instead of sizing a recreational suit from a racing-suit expectation.
Editorial note
We use these guides to narrow the starting range. Before you buy, compare that range with the exact brand chart, hands-on fit checks, and current sport rules. Read more about how our sizing works.
Spot a range that looks off, or a league rule we should mention? Tell us — corrections make these guides better for every parent.
Step 1
Find the likely size range
Swipe the table left to see every column.
| Speedo size / U.S. age label | Official body measurements | How to use this row |
|---|---|---|
| 22 / U.S. 4 years | Chest 20.5-22 in; waist 20.5-21 in; hips 21.5-23 in | Use only for the cited model and choose from measurements, not the age label alone. |
| 24 / U.S. 6 years | Chest 22.5-24 in; waist 21.5-22 in; hips 23.5-25 in | Re-open the current product chart before ordering in case the model or chart changes. |
| 26 / U.S. 8 years | Chest 24.5-26 in; waist 22.5-23.5 in; hips 25.5-27.5 in | Confirm straps and leg openings lie flat without digging or gaping. |
| 28 / U.S. 10 years | Chest 26.5-28.5 in; waist 24-25 in; hips 28-30 in | A full arm rotation should not make the suit pull or ride up. |
| 30 / U.S. 12 years | Chest 29-31 in; waist 25.5-26.5 in; hips 30.5-33 in | If measurements cross rows, use the exact seller's guidance and try adjacent sizes when possible. |
| 32 / U.S. 14 years | Chest 31.5-33.5 in; waist 27-28 in; hips 33.5-35.5 in | Do not transfer this number to another Speedo line or another brand. |
| 34 / U.S. 16 years | Chest 34-36 in; waist 28.5-29.5 in; hips 36-38 in | Racing and Fastskin products use dedicated sizing; use their separate chart. |
Source context: The numeric rows reproduce the official chart shown for Speedo's Girls Hyperboom Butterfly Back one-piece. They are a model-specific example, not a universal kids' swimsuit conversion; open the current chart for the exact suit before ordering.
Step 2
Measure for the exact swimsuit chart
Points to measure
Swimsuit fit checkpoints
Check both chest and waist — they sometimes fall in different sizes.
- 1. Chest circumference: Measure around the widest point, tape level.
- 2. Waist: Measure at the narrowest point of the torso.
- 3. Movement check: Suit stays secure through a push-off and arm stroke.
- 1. Use a soft tape over bare skin or close-fitting clothing. Keep it flush without pulling it tight, take each measurement twice, and use the larger result if the two attempts differ.
- 2. Measure the fullest part of the chest with the tape level, the narrowest point of the natural waist, and the fullest part of the hips and seat with feet together.
- 3. Open the current chart attached to the exact product and compare all required measurements; do not select from age alone.
- 4. Try the suit dry: straps and openings should lie flat, and the swimmer should be able to complete a full arm rotation without the suit riding up.
Step 3
Validate the fit before you shop
Good reasons
When to try another swimsuit size or model
- The exact chart places a required body measurement outside the selected row.
- Straps or leg openings dig in, leave deep marks quickly, or restrict movement.
- The swimmer cannot lift and rotate both arms without the suit pulling or riding up.
- Try a smaller or differently shaped model instead when fabric gaps, puckers, or straps slip.
Avoid these
Common mistakes
- Choosing from an age label without taking the measurements required by the exact chart.
- Copying one model's Speedo size number to another line or brand.
- Applying standard kids' sizing to a racing or Fastskin suit with a dedicated compression chart.
Parent tip
Keep the tags on until the swimmer can lift both arms, rotate the shoulders, bend, and sit without gaps, slipping straps, deep marks, or restricted movement.
When the checks agree
Compare options that match the checked size
Use the range above as a starting point, then recheck the exact product's brand chart before ordering.
Browse optional swimsuit picksFAQ
What measurements determine a kids' swimsuit size?
Use the measurements required by the exact product chart. Speedo's cited girls' model uses chest, waist, and hips, while other products can add height, weight, or a body-loop measurement.
Should a kids' swimsuit feel tight?
It should lie close to the body and stay in place, but it should not restrict a full arm rotation, cause deep marks, or cut off circulation. Training and racing suits can have different intended fits, so check the product type.
What if chest, waist, and hips fall in different rows?
Do not guess from age. Follow the exact model's current fit guidance and try adjacent sizes when possible; keep the size that lies flat and allows full movement without gaps or painful pressure.
Provenance
Sources used for this sizing guide
We use chest, waist, and hip measurements on the exact product chart, then verify that straps and openings stay flat while the swimmer can complete a full arm rotation.
Speedo
ManufacturerSupports: Swimwear measurement method; Recreation training fit difference; Swimsuit fit checks
Reviewed August 2026
Speedo
ManufacturerSupports: Model specific girls size ranges; Chest waist hip chart
Reviewed August 2026
Know your child's starting size before you shop.
Pick the sport and gear, then add the measurements that matter. You'll get a practical starting range, fit checks, and what to avoid.