Your skin tans because of UVA rays. These are the party animals—they dive deep into your skin and cause that golden glow (and, let’s be honest, a bit of premature aging). The good news? Regular window glass lets UVA rays pass through. So that sunbeam on your face? It’s carrying the real deal.
Meanwhile, the UVB rays are the muscle-bound bouncers at the club door. UVB rays are the ones that give you a sunburn and help your body make Vitamin D. Most glass completely blocks UVB rays. So you won’t crisp up like a lobster, but you also won’t get that happy Vitamin D boost. It’s a trade-off, like ordering a salad but skipping the dressing.
I once spent a whole afternoon reading by a sunny window during a pandemic. I was convinced I’d emerge looking like a bronze statue. Instead, I looked exactly the same, except my left arm felt slightly warmer than my right. It was the most anti-climactic glow-up ever.
Location, Location, Location
Here’s where it gets trickier than ordering coffee with a hangover. Not all windows are created equal. A car windshield is specially laminated to block almost all UVA rays. So, unless you’re driving a sunroof convertible and holding your arm up like a trophy, you’re not tanning from your commute. You’re just sitting in a hot box.
Can You Get a Tan Through a Window? Plus 3 Other FAQs
But your side windows at home? Those are usually plain glass. That’s your golden ticket. If you position your lounge chair next to a big, uncoated window, you are absolutely getting some UV action. Just don’t expect a deep, vacation-level tan. It’s more like a suggestion of a tan.
My friend Karen once claimed she got “window stripes” on her arms from driving a delivery truck for a month. I squinted. They looked suspiciously like the tan lines you get from a t-shirt. We agreed to call it a “proximity bronze.” It sounded fancier.
