Kids Rashguards UPF50+: How to Spot the Real Thing

Why Many Kids Rashguards Don't Actually Block UV (And How to Tell the Difference)

The short answer: the word “rashguard” has no UV requirement attached to it. A long-sleeve swim top can be sold as a rashguard with no UV testing whatsoever. To know whether the one in your hand actually blocks UV, you need to ask two specific questions, and many brands can’t answer them.

A Real Story That Should Not Be Possible

A friend recently bought a kids long-sleeve swim top from a well-known high-street store. It was marketed as a UV swim top. Her son wore it all day at the beach. That evening, the skin under the fabric was red and breaking out, a sunburn through the garment that was supposed to prevent exactly that.

This is not a freak accident. It is what happens when a long-sleeve swim top is marketed as UV-protective without ever being independently tested. The problem is, the buyer has no easy way to tell the two apart on a hanger.

“Rashguard” Is Not a Protection Standard

A rashguard was originally a surfer’s garment: a long-sleeve top worn under a wetsuit to prevent skin chafing from board wax and neoprene. The word describes the shape and intended use, not the protection level.

Today, almost any long-sleeve swim top can be called a rashguard. Some are made from technical fabrics that have been laboratory-tested for UV transmission. Many are not. Both share the same product category and often the same price point.

What “UPF50+” Actually Has to Mean

UPF stands for Ultraviolet Protection Factor. A UPF50+ rating means the fabric blocks at least 98% of UV radiation. But the rating only carries meaning if it has been verified by an independent laboratory against a recognised standard.

There are three standards that count internationally:

• AS/NZS 4399:2017 — Australia and New Zealand

• EN 13758-1:2002 — Europe

• AATCC TM183 — United States

A swimsuit tested to all three has been independently verified in three different jurisdictions, by three different methods. That is real protection. A swimsuit with a UPF claim and no named standard has been verified by no one.

Structural UPF vs Coating: A Critical Distinction

There are two ways a fabric can achieve a UPF rating. Both can show UPF50+ on the label when new. Only one keeps working over time.

Structural UPF

The UV protection is built into the yarn itself — the fibres are dense enough, or the weave is tight enough, to physically block UV light. This protection lasts the lifetime of the garment. Washing, sun exposure and chlorine do not degrade it.

Coated UPF

A chemical finish is applied to the surface of the fabric after manufacture. It is cheaper to produce. It works initially. But like any chemical coating, it degrades — typically within 20 to 30 washes. By the start of the second summer, the protection may be largely gone, even though the garment still looks identical.

The label rarely tells you which one you’re buying. You have to ask.

Beyond UV: What Sits Against Your Child’s Skin All Day

A rashguard is worn for hours, often wet, in direct contact with skin. The chemical composition of the fabric matters as much as the UV protection.

OEKO-TEX® Standard 100 is the most recognised global certification for textile safety. It tests for over 1,000 substances harmful to human health. Within the standard there are four product classes, and the strictest is Class 1 — the level required for fabrics that touch the skin of babies and very young children.

A rashguard with OEKO-TEX Class 1 has been certified to the same chemical safety standard as a newborn’s clothing. A rashguard with no OEKO-TEX certification has been tested to no chemical safety standard at all.

Recycled Doesn’t Mean Compromised

A common assumption: recycled fabric must be lower quality than virgin material. For technical swimwear, this is no longer true.

ECONYL® regenerated nylon is made from recovered ocean fishing nets, industrial nylon waste and post-consumer plastics. It is chemically identical to virgin nylon, the same strength, the same elasticity, the same resistance to chlorine and sun creams. It is used in high-end activewear, surf brands and luxury swimwear precisely because performance is not compromised.

The marker to look for is GRS, Global Recycled Standard certification. GRS verifies the recycled content claim through every step of the supply chain. Without it, “recycled” is just a word on a label.

The Checklist: Two Questions That Tell You Everything

Next time you’re holding a kids rashguard and trying to decide if it’s worth the price, ask the brand these two questions. Their answers, or their inability to answer, will tell you most of what you need to know.

If a brand cannot tell you which UPF standard their fabric is tested to, the answer is functionally none. If they cannot tell you whether the UPF is structural or coated, you are buying on hope. If they cannot specify the OEKO-TEX class, the chemical safety is unverified.

How MIKOU Answers These Questions

Our rashguards are made from VITA fabric: 78% ECONYL® regenerated nylon, recovered from ocean fishing nets and plastic waste.

• UPF50+ tested to all three international standards: AS 4399:2020, EN 13758-1:2007, AATCC TM183:2020;

• Structural UPF: built into the yarn, not applied as a coating;

• OEKO-TEX® Standard 100 Product Class 1: the strictest chemical safety class, required for newborn fabrics;

• GRS certified: every fibre tracked through the supply chain;

• Made in Portugal, in a family-run atelier working to EU standards.

We make two rashguards, long-sleeve swim tops for kids ages 4 to 10. The same fabric, the same certifications, in two colours, and they do exactly what the label says.