Why ISO 12312-2 is the only filter standard you should trust

When people search for eclipse glasses, they're bombarded with claims — "NASA approved," "100% UV protection," "CE certified." Most of these claims are either misleading or meaningless on their own. There is exactly one standard that actually matters for direct solar viewing: ISO 12312-2:2015.

Here's why this standard exists and why nothing else comes close.

What ISO 12312-2 actually tests

ISO 12312-2:2015 is the international standard specifically written for filters used for direct observation of the sun. It sets strict limits on how much visible light, ultraviolet radiation, and infrared radiation can pass through a lens. To meet the standard, a filter must block all but a tiny fraction of sunlight — dark enough that the sun appears as a comfortable, dim disc rather than a blinding source of light.

Crucially, the standard doesn't just test visible light. Many cheaper filters that look "dark enough" to the naked eye still allow dangerous levels of UV and infrared radiation through — radiation your eye cannot detect but that causes real damage to the retina over time. ISO 12312-2 testing catches exactly this gap.

Why "NASA approved" is not a real certification

NASA does not certify, test, or approve eclipse glasses. NASA's website provides general safety guidance and points people toward the ISO 12312-2 standard, but there is no NASA seal of approval, no NASA testing lab, and no NASA registry of approved manufacturers. Any product marketed as "NASA approved" is making a claim that NASA itself does not make.

What to actually check before buying

Look for explicit reference to ISO 12312-2:2015 on the product and packaging — not just "ISO certified" with no number. Ask whether the manufacturer can provide test reports or a certificate of conformity. At Exclipse, every pair we supply is manufactured to ISO 12312-2:2015, and our certification documentation is available to download on our Certifications page for anyone — individual buyers, schools, or wholesale partners — who wants to verify before they buy.

With the 2026 total solar eclipse approaching, the market will fill up with products making vague safety claims. Knowing what ISO 12312-2 actually means is the single most useful thing you can learn before choosing eclipse glasses for yourself, your family, your classroom, or your customers.