Funky Trunks Boys Size Guide

This size guide covers Funky Trunks Boys Training Swimwear, including the Training Jammer and Sidewinder Trunks. Both styles are made from ECO C-Infinity fabric — the same superior quality polyester construction as C-Infinity, manufactured from end-of-life plastic water bottles. Providing 100% chlorine resistance, 50+ UV sun protection, and exceptional colour fastness. Fabric milled in Italy.

Size based on waist and hip measurements. Funky Trunks boys' swimwear is available in sizes 22–30, covering junior swimmers from approximately 6 to 14 years.

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How to Measure — Funky Trunks Boys
How to measure for Funky Trunks boys swimwear

Measure in centimetres with a soft tape measure taken directly against the skin or over light underwear. Use both measurements to find the best fit in the table below.

  • Waist — measure around the narrowest part of the waistline, usually just above the belly button. Keep the tape parallel to the floor.
  • Hips — measure around the fullest part of the hips and seat. Keep the tape parallel to the floor and ensure it sits flat all the way around.
  • If your measurements fall between two sizes, speak to a member of staff at Allens for advice on the best fit for the specific style.
Size 22 24 26 28 30
UK 22 24 26 28 30
US 22 24 26 28 30
AUS 6 / 22 8 / 24 10 / 26 12 / 28 14 / 30
France 6 ans 8 ans 10 ans 12 ans 14 ans
Body Measurements (cm)
Waist (cm) 55–60 60–65 65–70 70–75 75–80
Hips (cm) 60–65 65–70 70–75 75–80 80–85

UK and US sizes are equivalent and used as the primary reference. Always measure waist and hips for the most accurate fit. If between sizes, speak to a member of staff at Allens.

Training Jammer — Key Features
  • Hip-to-knee coverage with a smooth fit — designed for young competitive swimmers who want performance-focused coverage during training.
  • Flatlock stitching reduces seam bulk and minimises irritation during long training sessions.
  • Drawcord and flat elastic waistband for a secure, adjustable fit during dives and turns.
  • Front pouch lining for added comfort and support.
  • ECO C-Infinity fabric — 100% chlorine resistant, 50+ UV protection, made from recycled plastic bottles. 100% polyester, fabric milled in Italy.
Sidewinder Trunks — Key Features
  • 12cm sides (slightly larger on larger sizes) for a comfortable, practical coverage that suits training and recreational swimming.
  • Single front panel with full front lining for a clean, comfortable fit.
  • Drawcord waist with wide elastic leg opening for ease of movement.
  • High definition colour fastness — Funky Trunks prints are designed to stay vibrant with regular pool use.
  • ECO C-Infinity fabric — 100% chlorine resistant, 50+ UV protection, made from recycled plastic bottles. 100% polyester, fabric milled in Italy.
Fit Notes — Funky Trunks Boys Swimwear
  • Size based on waist and hip measurements. If measurements suggest different sizes, use the waist measurement as the primary guide for trunks and the hip measurement as the primary guide for jammers.
  • The Training Jammer is designed for young competitive swimmers — it provides hip-to-knee coverage and a close fit. If your child is new to jammers, check the hip measurement carefully.
  • The Sidewinder Trunks are more relaxed in fit with a wider elastic leg opening — a good choice for swimmers who prefer the freedom of a trunk over a jammer.
  • ECO C-Infinity fabric is 100% chlorine resistant and built for regular training. Rinse in cold fresh water after every session and allow to dry naturally away from direct sunlight.
  • Unsure? Contact our team or call +44 1827 330600.
Frequently Asked Questions — Funky Trunks Boys Swimwear

Measure your child's waist and hips in centimetres and match to the size table above. UK sizing is the primary reference — US, AUS, and France equivalents are also shown. If measurements fall between two sizes, speak to a member of staff at Allens for advice.

The Training Jammer provides hip-to-knee coverage with flatlock stitching and a front pouch lining — designed for young competitive swimmers focused on performance. The Sidewinder Trunks are a shorter style with 12cm sides, a single front panel, and a wider elastic leg opening — better suited to swimmers who prefer the freedom and practicality of a trunk for training and recreational use.

ECO C-Infinity is Funky Trunks' premium chlorine-resistant polyester fabric, manufactured from end-of-life plastic water bottles. It offers the same superior quality and performance as the standard C-Infinity fabric — 100% chlorine resistance, 50+ UV sun protection, and exceptional colour fastness — while reducing environmental impact by giving new life to waste plastics. The fabric is milled in Italy.

The Funky Trunks Training Jammer is a training swimsuit designed for regular pool use. It is not a FINA-approved racing suit and should not be used for competition. For competitive racing, a World Aquatics-approved racing jammer is required. The Training Jammer is, however, an excellent choice for club training and squad sessions.

Rinse in cold fresh water after every session to remove chlorine and salt. Allow to dry naturally away from direct sunlight — do not tumble dry or wring the fabric. The ECO C-Infinity fabric is 100% chlorine resistant and designed for regular pool use. With proper care the prints and fabric will maintain their quality for longer.

The boys' size range covers sizes 22 to 30, corresponding approximately to ages 6 to 14. However, children develop at different rates and age is only a rough guide — always measure waist and hips using the size table above for the most accurate fit. Size 30 transitions into adult sizing for some styles.

Flatlock stitching is a technique where the seams lie flat against the skin rather than creating a raised ridge. This reduces rubbing and irritation during long training sessions, making it particularly useful for young swimmers doing high volumes of pool work. It also contributes to a smoother, more streamlined feel in the water.