If you've started looking at solar eclipse glasses for the August 2026 eclipse, you've probably already seen labels like "NASA approved," "100% UV protection," or "CE certified" scattered across listings. Some of these claims are misleading. One of them isn't even real. There is exactly one standard that actually matters when it comes to protecting your eyes during direct solar viewing: EN ISO 12312-2:2015.
Here's what it actually means, and why it's the only thing worth checking before you buy.
What EN ISO 12312-2 actually tests
This is the international standard written specifically for filters used to look directly at the sun. It sets strict limits on how much visible light, ultraviolet radiation, and infrared radiation a lens is allowed to let through. To pass, a filter has to be dark enough that the sun appears as a small, comfortable, dim disc — never blinding, never uncomfortable.
The part most people don't realise: it's not just about how dark the lens looks. Plenty of cheap, very dark filters still let through dangerous levels of UV and infrared light — radiation your eyes can't detect, but that can cause lasting retina damage over time. A lens can look "dark enough" and still fail this test. EN ISO 12312-2 is designed to catch exactly that gap.
Why "NASA approved" isn't a real thing
NASA does not test, certify, or approve eclipse glasses. Their website offers general safety information and points people toward the ISO 12312-2 standard — but there's no NASA seal, no NASA testing lab, and no official NASA list of approved brands. If you see "NASA approved" on a product, that's a claim NASA itself doesn't make.
What to actually look for before buying
Check for an explicit reference to EN ISO 12312-2:2015 — not just "ISO certified" with no number attached, which tells you nothing. If you're buying in larger quantities for a school, store, or event, it's worth asking whether the seller can provide test reports or a certificate of conformity.
At SolarOptics, every pair we supply is manufactured to EN ISO 12312-2:2015, and our full certification documentation is available to download on our Certifications page — whether you're buying a single pair for yourself or placing a wholesale order for your business.
Our certification documents include the full EN ISO 12312-2:2015 test report alongside our CE and UKCA declarations — three separate documents covering three separate markets, because "certified" without specifying which certification and for which region doesn't tell you much either. If you're a parent checking before a family purchase, a teacher sourcing for a classroom, or a buyer comparing suppliers for a larger order, you can open each document directly rather than taking a logo at face value.
As the 2026 total solar eclipse gets closer, the market is going to fill up fast with products making vague, feel-good safety claims. Knowing what EN ISO 12312-2 actually means might be the single most useful five minutes you spend before choosing glasses for yourself, your kids, or your classroom.