If you have ever stood in a shop turning a kids hat over in your hands, you have seen it: a little tag that says UPF 50+. It sounds reassuring. It is meant to. But if someone asked you what it actually means, would you have an answer beyond "the good one"?
We didn't either, back when we were just parents buying hats rather than parents making them. So this is the post we wish we could have read: what UPF is, how a hat earns the 50+, how it's different from the SPF on your sunscreen, and what the label doesn't tell you. No jargon, no lecture, just the useful bits.
UPF, in one sentence
UPF stands for Ultraviolet Protection Factor. It measures how much of the sun's UV radiation a fabric lets through to the skin underneath. That's it. It's a rating for material, the same way SPF is a rating for sunscreen.
The number tells you the fraction. A fabric rated UPF 50 lets through roughly 1/50th of the UV that hits it, which is about 2 percent. Put another way, it blocks about 98 percent. UPF 50+ means the fabric tested at 50 or higher, and 50+ is the top of the scale. There is no UPF 80 or UPF 100 on a label, because once you're blocking 98 percent or more, the standard just calls it 50+ and stops counting.
So when you see UPF 50+ on a Luma hat, it means the fabric itself has been tested to let through no more than around 2 percent of UV. The rest gets stopped before it reaches their head, ears, and neck.
How a hat gets its UPF rating
This is the bit that surprised us. UPF isn't a marketing phrase a brand can just decide to print. In Australia and New Zealand it's set by a standard, AS/NZS 4399, and it's tested in a lab.
The short version of the test: a sample of the fabric is put in front of an instrument that shines UV light through it and measures what comes out the other side, across the wavelengths that reach us from the sun (both UVA and UVB). The result is calculated into a UPF number, and the fabric earns the label only if it clears the bar. Under the current version of the standard, a product can be labelled UPF 15, 30, 50 or 50+, with 50 and 50+ sitting in the top "excellent" bracket.
Every fabric we use across the Play Range and Splash Range is rated UPF 50+. It was the first thing we settled on, before colours, before the buckle, before the name. UPF 50+. Always.
UPF vs SPF: not the same thing
These two get mixed up constantly, and fair enough, they look like siblings. But they measure different things.
SPF (Sun Protection Factor) is for sunscreen. It's mostly about UVB, the rays that cause the redness, and it describes how much longer skin takes to burn with the product on versus bare, assuming it's applied properly and reapplied. In real life, most of us apply too little and forget to top up, which is why sunscreen usually delivers less than the number on the tube.
UPF is for fabric. It covers both UVA and UVB, and it doesn't wear off. A UPF 50+ hat doesn't need reapplying every two hours, doesn't sweat off in the sandpit, and doesn't get missed behind the ears because someone wriggled. If the fabric is between the sun and the skin, it's working.
That's why the two are best friends rather than rivals. Sunscreen covers the bits fabric can't (the face, the backs of hands). Fabric covers the bits sunscreen tends to miss (the scalp, the ears, the back of the neck). A hat is the easy half of that deal, because once it's on, the job's done. We'll dig into hats versus sunscreen for babies in a coming post.
What can change a fabric's UPF
A few things affect how much UV a fabric lets through, and they're worth knowing when you're comparing hats.
How tightly it's woven. The denser the weave or knit, the fewer gaps for UV to sneak through. Hold a fabric up to a window: if you can see a lot of light coming through, so can UV.
Colour. Darker and more saturated colours generally absorb more UV than pale ones made from the same fabric. That doesn't mean a light hat is a bad hat, only that a light hat needs to be a good, dense fabric to earn its rating (ours are tested regardless of colour).
Stretch. Pulling a fabric tight opens up the weave. This matters more for swimwear than hats, but it's another reason a hat that fits properly, rather than one stretched over a head two sizes too big, does its job better. Our Find Their Fit guide has the two-minute string trick for measuring.
Wet versus dry. Some fabrics lose a bit of UPF when they're soaked through, especially lighter cottons. That's exactly why we built the Splash Range in a quick-dry fabric that's rated UPF 50+ for the water, not just the walk to it.
Wear and tear. Fading, thinning and stretching over years can lower UPF a little. A hat that's been through three summers and a dozen washes is still doing a lot, but it's a fair reason to check the fabric hasn't gone see-through at the crown.
What UPF 50+ doesn't tell you
Here's the honest bit. UPF is a rating for the fabric, not for the hat's shape. A UPF 50+ fabric cut into a tiny cap with no brim keeps UV off the crown of the head and not much else. The face, ears and neck are only shaded if the design actually shades them.
So the label is where you start, not where you stop. The other things that decide how much sun stays off a kid are the width of the brim, whether the neck is covered (a legionnaire flap or a wide bucket brim both do this), and, more than anything, whether the hat is still on their head at 3pm. A hat in the bottom of the pram has a UPF of zero.
That last one is the whole reason Luma exists. A UPF 50+ fabric only counts for the hours it's being worn, so we spent most of our design time on the part nobody rates in a lab: the buckle that tiny hands can't undo. Kids hats that stay on. Finally. If yours has been winning the hat fight lately, we wrote about why kids hate hats and what finally worked for ours, and a longer playbook on how to keep a hat on a toddler.
The short version
UPF 50+ means the fabric has been lab-tested to let through around 2 percent of UV or less, the highest rating there is. It's about material, not sunscreen, and it doesn't wear off. Look for it on the tag, then check the brim, check the neck, check the fit, and pick the hat they'll actually keep on. That's the difference between five more minutes and the whole afternoon.
For more on reading UV levels, when the sun is strongest, and why cloudy days count too, our UV Guide has it in plain English. And if you try a Luma and it isn't right for your kid, our money-back guarantee has you covered.
Ready for more hat days? Shop the Play Range. UPF 50+. Always.
What does UPF 50+ mean on a kids hat?
UPF stands for Ultraviolet Protection Factor. UPF 50+ means the fabric has been lab-tested to let through around 2 percent of UV or less, blocking about 98 percent. It is the highest rating on the scale used in Australia and New Zealand.
Is UPF the same as SPF?
No. SPF rates sunscreen and describes how much longer skin takes to burn with the product on. UPF rates fabric and measures how much UVA and UVB gets through the material. UPF doesn't wear off or need reapplying while the fabric is worn.
Does a UPF 50+ hat block all UV?
No fabric blocks 100 percent. UPF 50+ fabric lets through around 2 percent or less. The bigger question is coverage: UPF only applies to the skin the fabric actually covers, so brim width, neck coverage and whether the hat stays on all matter as much as the label.
Does UPF wear off over time or when the fabric is wet?
UPF is built into the fabric, so it doesn't wash out the way sunscreen wears off. Some fabrics lose a little when soaked or stretched, and years of fading and thinning can lower it. Quick-dry fabrics rated for water, like the Luma Splash Range, are designed to keep their rating wet.
Related posts:
Why Kids Hate Hats -- How to Keep a Hat on a Toddler
What Does UPF 50+ Actually Mean?
If you have ever stood in a shop turning a kids hat over in your hands, you have seen it: a little tag that says UPF 50+. It sounds reassuring. It is meant to. But if someone asked you what it actually means, would you have an answer beyond "the good one"?
We didn't either, back when we were just parents buying hats rather than parents making them. So this is the post we wish we could have read: what UPF is, how a hat earns the 50+, how it's different from the SPF on your sunscreen, and what the label doesn't tell you. No jargon, no lecture, just the useful bits.
UPF, in one sentence
UPF stands for Ultraviolet Protection Factor. It measures how much of the sun's UV radiation a fabric lets through to the skin underneath. That's it. It's a rating for material, the same way SPF is a rating for sunscreen.
The number tells you the fraction. A fabric rated UPF 50 lets through roughly 1/50th of the UV that hits it, which is about 2 percent. Put another way, it blocks about 98 percent. UPF 50+ means the fabric tested at 50 or higher, and 50+ is the top of the scale. There is no UPF 80 or UPF 100 on a label, because once you're blocking 98 percent or more, the standard just calls it 50+ and stops counting.
So when you see UPF 50+ on a Luma hat, it means the fabric itself has been tested to let through no more than around 2 percent of UV. The rest gets stopped before it reaches their head, ears, and neck.
How a hat gets its UPF rating
This is the bit that surprised us. UPF isn't a marketing phrase a brand can just decide to print. In Australia and New Zealand it's set by a standard, AS/NZS 4399, and it's tested in a lab.
The short version of the test: a sample of the fabric is put in front of an instrument that shines UV light through it and measures what comes out the other side, across the wavelengths that reach us from the sun (both UVA and UVB). The result is calculated into a UPF number, and the fabric earns the label only if it clears the bar. Under the current version of the standard, a product can be labelled UPF 15, 30, 50 or 50+, with 50 and 50+ sitting in the top "excellent" bracket.
Every fabric we use across the Play Range and Splash Range is rated UPF 50+. It was the first thing we settled on, before colours, before the buckle, before the name. UPF 50+. Always.
UPF vs SPF: not the same thing
These two get mixed up constantly, and fair enough, they look like siblings. But they measure different things.
SPF (Sun Protection Factor) is for sunscreen. It's mostly about UVB, the rays that cause the redness, and it describes how much longer skin takes to burn with the product on versus bare, assuming it's applied properly and reapplied. In real life, most of us apply too little and forget to top up, which is why sunscreen usually delivers less than the number on the tube.
UPF is for fabric. It covers both UVA and UVB, and it doesn't wear off. A UPF 50+ hat doesn't need reapplying every two hours, doesn't sweat off in the sandpit, and doesn't get missed behind the ears because someone wriggled. If the fabric is between the sun and the skin, it's working.
That's why the two are best friends rather than rivals. Sunscreen covers the bits fabric can't (the face, the backs of hands). Fabric covers the bits sunscreen tends to miss (the scalp, the ears, the back of the neck). A hat is the easy half of that deal, because once it's on, the job's done. We'll dig into hats versus sunscreen for babies in a coming post.
What can change a fabric's UPF
A few things affect how much UV a fabric lets through, and they're worth knowing when you're comparing hats.
How tightly it's woven. The denser the weave or knit, the fewer gaps for UV to sneak through. Hold a fabric up to a window: if you can see a lot of light coming through, so can UV.
Colour. Darker and more saturated colours generally absorb more UV than pale ones made from the same fabric. That doesn't mean a light hat is a bad hat, only that a light hat needs to be a good, dense fabric to earn its rating (ours are tested regardless of colour).
Stretch. Pulling a fabric tight opens up the weave. This matters more for swimwear than hats, but it's another reason a hat that fits properly, rather than one stretched over a head two sizes too big, does its job better. Our Find Their Fit guide has the two-minute string trick for measuring.
Wet versus dry. Some fabrics lose a bit of UPF when they're soaked through, especially lighter cottons. That's exactly why we built the Splash Range in a quick-dry fabric that's rated UPF 50+ for the water, not just the walk to it.
Wear and tear. Fading, thinning and stretching over years can lower UPF a little. A hat that's been through three summers and a dozen washes is still doing a lot, but it's a fair reason to check the fabric hasn't gone see-through at the crown.
What UPF 50+ doesn't tell you
Here's the honest bit. UPF is a rating for the fabric, not for the hat's shape. A UPF 50+ fabric cut into a tiny cap with no brim keeps UV off the crown of the head and not much else. The face, ears and neck are only shaded if the design actually shades them.
So the label is where you start, not where you stop. The other things that decide how much sun stays off a kid are the width of the brim, whether the neck is covered (a legionnaire flap or a wide bucket brim both do this), and, more than anything, whether the hat is still on their head at 3pm. A hat in the bottom of the pram has a UPF of zero.
That last one is the whole reason Luma exists. A UPF 50+ fabric only counts for the hours it's being worn, so we spent most of our design time on the part nobody rates in a lab: the buckle that tiny hands can't undo. Kids hats that stay on. Finally. If yours has been winning the hat fight lately, we wrote about why kids hate hats and what finally worked for ours, and a longer playbook on how to keep a hat on a toddler.
The short version
UPF 50+ means the fabric has been lab-tested to let through around 2 percent of UV or less, the highest rating there is. It's about material, not sunscreen, and it doesn't wear off. Look for it on the tag, then check the brim, check the neck, check the fit, and pick the hat they'll actually keep on. That's the difference between five more minutes and the whole afternoon.
For more on reading UV levels, when the sun is strongest, and why cloudy days count too, our UV Guide has it in plain English. And if you try a Luma and it isn't right for your kid, our money-back guarantee has you covered.
Ready for more hat days? Shop the Play Range. UPF 50+. Always.
What does UPF 50+ mean on a kids hat?
UPF stands for Ultraviolet Protection Factor. UPF 50+ means the fabric has been lab-tested to let through around 2 percent of UV or less, blocking about 98 percent. It is the highest rating on the scale used in Australia and New Zealand.
Is UPF the same as SPF?
No. SPF rates sunscreen and describes how much longer skin takes to burn with the product on. UPF rates fabric and measures how much UVA and UVB gets through the material. UPF doesn't wear off or need reapplying while the fabric is worn.
Does a UPF 50+ hat block all UV?
No fabric blocks 100 percent. UPF 50+ fabric lets through around 2 percent or less. The bigger question is coverage: UPF only applies to the skin the fabric actually covers, so brim width, neck coverage and whether the hat stays on all matter as much as the label.
Does UPF wear off over time or when the fabric is wet?
UPF is built into the fabric, so it doesn't wash out the way sunscreen wears off. Some fabrics lose a little when soaked or stretched, and years of fading and thinning can lower it. Quick-dry fabrics rated for water, like the Luma Splash Range, are designed to keep their rating wet.
Related posts:
Why Kids Hate Hats -- How to Keep a Hat on a Toddler