Size chart

This size guide covers the Arena Powerskin ST Next Boys’ Jammer — the next generation of Arena’s iconic ST racing suit and the first ever World Aquatics (FINA) approved racing suit made with recycled fabrics. Made from over 60% recycled fibre from waste yarns, the ST Next delivers sustainable performance without compromise.

The new fabric is significantly lighter and faster than its predecessor, absorbing less water and reducing drag for longer-lasting compression and enhanced durability race after race. Designed with low-profile seams for perfect fit and outstanding freedom of movement. An excellent choice for junior swimmers competing at club, county, or regional level. All measurements are body measurements taken directly from your child’s body. Use the Hip (B) as the primary sizing guide. Age ranges are shown as a guide only.

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Body Measurement Points
Arena Arena Powerskin ST Next Boys' Jammer boys body measurement points — waist and hip
How to Measure

Take all measurements directly against your child’s skin using a soft tape measure. Use the Hip (B) as the primary sizing guide. Age is shown as a guide only — always use body measurements as children develop at very different rates.

  • A
    WaistMeasure at the narrowest part of the natural waist, keeping the tape horizontal and level.
  • B
    HipMeasure around the fullest, widest part of the hips and seat, keeping the tape horizontal.

If measurements fall between sizes, speak to a member of staff at Allens who will be happy to advise on the best fit.

Sizing Table — Arena Powerskin ST Next Boys' Jammer
Sizing 22 24 26 28
International Size Equivalents
UK 22 / 6–7 yrs 24 / 8–9 yrs 26 / 10–11 yrs 28 / 12–13 yrs
USA 22 24 26 28
France / Italy 6–7 yrs 8–9 yrs 10–11 yrs 12–13 yrs
Germany (height cm) 116 128 140 152
Body Measurements (cm)
A — Waist 54–56 56–59 59–62 62–65
B — Hip 60–64 65–69 71–75 78–82

Age ranges are a guide only. All measurements are body measurements, not garment measurements. Use the Hip (B) as the primary sizing guide. Speak to a member of staff at Allens if you are unsure.

Fit Notes — Arena Powerskin ST Next Boys' Jammer
  • Always use body measurements to select the correct size — age ranges are a guide only as children develop at very different rates.
  • Use the Hip (B) as the primary sizing guide — the jammer needs to seat correctly over the hips before the waistband can sit flat.
  • If measurements fall between sizes, speak to a member of staff at Allens who will be happy to advise on the best fit.
  • The recycled eco-friendly fabric is lighter and faster than the previous ST generation — the suit should feel close-fitting and supportive with excellent freedom of movement throughout a full competition day.
  • Low-profile seams should lie completely flat against the skin with no rubbing or pressure points during competition — particularly important for younger swimmers in longer events.
  • The ST Next’s longer-lasting compression means the suit retains its performance properties race after race, making it a reliable choice for the competitive season.
  • The suit should be completely wrinkle-free when correctly fitted — any bunching or gathering indicates the suit is too large.
  • The waistband should sit flat with no rolling. Leg hems should end above the knee in line with World Aquatics regulations.
  • Allow 10–15 minutes to put on correctly for the first time. Take care with fingernails and jewellery to protect the fabric.
  • Do not use sunscreen, oils, or petroleum-based products before putting on the suit as these degrade the fabric.
  • Rinse in cold fresh water immediately after each use. Do not machine wash, tumble dry, iron, or dry-clean.
  • Unsure? Contact our team or call +44 1827 330600. Speak to a member of staff at Allens if you are unsure.
Frequently Asked Questions — Arena Powerskin ST Next Boys' Jammer

Measure your child’s waist (A) and hip (B) using a soft tape measure directly against the skin. Use the hip measurement as the primary guide and compare both to the sizing table above. Age is shown as a guide only — always use body measurements as children develop at very different rates. Speak to a member of staff at Allens if you are unsure.

Always select by body measurements. The age ranges shown are a guide only — children develop at very different rates and age alone is not a reliable indicator of the correct size. Measure the waist and hip and compare to the sizing table, using the hip as the primary guide.

If your child’s measurements fall between two sizes, speak to a member of staff at Allens who will be happy to advise on the best fit. Arena racing jammers are designed to fit closely — a suit that fits correctly should feel firm and supportive without restricting breathing or movement.

A junior racing jammer should feel firm and compressive but comfortable throughout a full competition day. It should be completely wrinkle-free when correctly fitted — any bunching or gathering indicates the suit is too large. The waistband should sit flat with no rolling, and leg hems should end above the knee in line with World Aquatics regulations.

Yes — the Arena Powerskin Impulso and ST Next meet FINA/World Aquatics specifications and are approved for use in all sanctioned competitive swimming events. Always check with your event organiser for any local age group rules regarding tech suits in competition. Speak to a member of staff at Allens if you need further guidance.

Arena racing jammers are competition suits and are not designed for regular training use. Using a tech suit for training will degrade the fabric and reduce its lifespan significantly. Reserve it for races and competition warm-ups. Arena offer a wide range of junior training jammers for everyday pool use.

Rinse the suit in cold fresh water immediately after every use. Do not machine wash, tumble dry, iron, or dry-clean. Store flat and dry, away from direct sunlight. Avoid contact with sunscreen, oils, and petroleum-based products. Do not wring or twist the suit. Handle with care when putting on and taking off to protect the fabric.

Arena junior racing suit sizes (22–28) do not directly correspond to standard clothing sizes. The sizing is based on body measurements — always use waist and hip measurements to select the correct size. The international size equivalents shown in the table are provided as a secondary reference only.

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