Tember Galaxy solar eclipse glasses, certified to EN ISO 12312-2 (Image: Tember)

ISO 12312-2 Explained: What the Eclipse-Glasses Standard Requires, and How to Check a Certificate

ISO 12312-2 is the international safety standard for filters made for looking directly at the Sun, such as eclipse glasses and hand-held solar viewers. It caps how much visible, ultraviolet and infrared light may pass, sets a minimum too (a filter can be too dark), and lists what must be printed on the product. In the EU it applies as EN ISO 12312-2:2015, and eclipse glasses are Category II protective equipment: a notified body must examine the design and issue an EU type-examination certificate before the CE mark can go on. ISO itself never certifies products. Below: what the standard requires, what must be printed, and how to check a certificate yourself in five minutes, using our own certificate as the worked example.

Last updated: 28 October 2026 (facts checked 27 October 2026)

What is ISO 12312-2?

Its full title is "Eye and face protection — Sunglasses and related eyewear — Part 2: Filters for direct observation of the sun". ISO published it in June 2015, and it covers "afocal products intended for direct observation of the Sun": glasses and viewers, not filters for telescopes, binoculars or cameras. ISO last reviewed and confirmed it in 2020, so the 2015 edition is still the current one.

A second edition is on its way. ISO's own page says the 2015 standard is "expected to be replaced by ISO/FDIS 12312-2 within the coming months", and the American Astronomical Society (AAS) says the new edition is being voted on by national standards bodies in 2026. Until it is published, glasses for 2 August 2027 are tested against the 2015 version. We will update this article when that changes.

In Europe the same text is adopted as EN ISO 12312-2:2015 (approved by CEN in April 2015), and national standards bodies publish it under their own prefix, for example DIN EN ISO 12312-2 in Germany. On European glasses you will usually see "EN ISO 12312-2:2015". Do not confuse it with ISO 12312-1, which covers ordinary sunglasses: Spain's National Geographic Institute (IGN) warns that glasses marked only "ISO 12312-1" are not suitable for looking at the Sun.

What does the standard actually require?

The text of ISO standards is sold, not free, so the summary below follows the AAS, which quotes the relevant clauses on its ISO 12312-2 page.

Main requirements of ISO 12312-2:2015 (as summarised by the AAS)

Requirement What the standard says Why it matters
Visible light, maximum Luminous transmittance no higher than 0.0032%, about the same as a shade 12 welding filter Keeps the Sun at a comfortable, safe brightness
Visible light, minimum A lower limit too, about the same as a shade 15 welding filter A filter that is too dark makes people tilt or lift the glasses to find the Sun
Ultraviolet (UVA and UVB) No higher than the measured luminous transmittance UV damage is invisible and painless
Infrared At most 3% Infrared heats the retina without you feeling it
Uniformity Luminous transmittance uniform to within 10% across the filter No brighter patches
Defects Free from bubbles, scratches, inclusions, dull spots, pitting and similar flaws; for metal-coated filters, no more than one pinhole up to 200 μm in any 5 mm circle A pinhole lets unfiltered sunlight through
Marking and instructions Manufacturer's name and address, instructions, warnings, storage advice and an obsolescence period (see below) You can trace who is responsible and how long the product is meant to last

Source: AAS, "ISO 12312-2 International Standard" (page updated 31 August 2026). The AAS gives no percentage for the minimum, only the shade equivalent, so we don't either. The AAS has proposed stricter limits for the revision (0.0012% and 0.00004%); these are proposals, not the current rule.

The minimum matters more than most buyers think. In summer 2026, Spanish consumer authorities withdrew several glasses models because their filters let through less light than the minimum: they were too dark, not too bright. Read what Spain's 2026 withdrawals teach about fake and non-compliant eclipse glasses.

What must be printed on ISO 12312-2 eclipse glasses?

Clause 5 of the standard lists the information that must be on the filter or its packaging, in the language of the country where it is sold. According to the AAS, that is:

  1. the name and address of the manufacturer;
  2. instructions for looking at the Sun or a solar eclipse;
  3. a warning that viewing the Sun without an appropriate filter can cause permanent eye injury;
  4. a warning that damaged filters, or filters separated from their mountings, should be discarded;
  5. advice on storage, cleaning and maintenance;
  6. an obsolescence deadline or period, where appropriate.

The last point is why there is no single "expiry date" for all eclipse glasses: each maker prints its own period. If you kept a pair from 2026, read our five checks before reusing 2026 eclipse glasses, and before every use do the checks in how to inspect eclipse glasses.

Does "ISO certified" mean anything?

Not on its own. ISO writes standards; it does not test products. ISO's own website says that "ISO does not perform certification or issue certificates" and that its logo "cannot be used by anyone outside of ISO". The AAS adds that no product should claim to be "ISO certified" and that no version of the ISO logo should appear on any product. Testing is done by independent laboratories, ideally ones accredited to ISO/IEC 17025.

So an ISO logo on the glasses is a warning sign, not a guarantee. And a printed "ISO 12312-2" is only a claim: as the AAS puts it, "anyone can print such a statement, but that doesn't make it true". In the EU, what turns the claim into something you can check is the certificate trail behind the CE mark.

Tember Galaxy solar eclipse glasses certified to EN ISO 12312-2, on a transparent background (Image: Tember)
Eclipse glasses sold in the EU must carry the CE mark, refer to EN ISO 12312-2 and name the manufacturer (Image: Tember)

How does the EU check eclipse glasses?

Eclipse glasses are personal protective equipment (PPE) under Regulation (EU) 2016/425. France's consumer authority, the DGCCRF, states that they are classed in risk category II. For category II, the Regulation (Article 19) requires two steps:

  • Module B, EU type-examination: a notified body, an independent organisation designated by an EU country and listed by the European Commission, examines and tests the design. If it passes, the body issues an EU type-examination certificate. The certificate must give the notified body's name and identification number, and it is valid for at most five years (Annex V).
  • Module C, conformity to type: the manufacturer then has to make sure that series production matches the examined type, under its own production control.

The manufacturer then draws up an EU declaration of conformity and affixes the CE mark. Two details surprise people:

  • On category II glasses, the CE mark stands alone. The four-digit number of a notified body follows the CE mark only on category III PPE (Article 17), so a missing number next to "CE" on eclipse glasses is normal.
  • The instructions must include the web address where the EU declaration of conformity can be found, unless the declaration comes with the product (Annex II, 1.4).

The weak point is module C. A certificate proves that the examined design passed; it does not test every production lot. That is why market surveillance authorities test samples, and why Spain withdrew particular lots in 2026.

How do you check an eclipse-glasses certificate, step by step?

  1. Read the glasses and the packaging. Look for the CE mark, "EN ISO 12312-2:2015" (not 12312-1), the manufacturer's name and address, and, if the maker is outside the EU, an EU address of the importer or authorised representative. Spain's consumer organisation OCU also advises looking for a lot number.
  2. Find the EU declaration of conformity. It comes in the box or at the web address given in the instructions. It should name the product, the Regulation (EU) 2016/425, the standard, and the notified body that issued the type-examination certificate.
  3. Look at the EU type-examination certificate. Check that it names a notified body with a four-digit number, covers the model you are buying, refers to EN ISO 12312-2:2015, and is still valid. Be wary of documents called "certificate of compliance" or "test report" from labs that are not notified: they can be genuine lab work, but they are not the EU type-examination certificate. A test report is evidence about the sample tested, nothing more.
  4. Look up the notified body. The European Commission's NANDO database (now part of the Single Market Compliance Space) lists every notified body with its number and the legislation and tasks it is notified for. The body should be notified under Regulation (EU) 2016/425 on personal protective equipment.
  5. Verify the certificate with the body itself, if it offers an online check where you type in the certificate number (CCQS, for example, has one).

Then check the product itself before every use. The DGCCRF suggests holding the glasses up to a lamp: if you see light or pinpoints through the filter, it is damaged. And look out for official warnings, such as the EU Safety Gate alerts on dangerous products and, in Spain, the RAPNA alert network.

What does a real certificate look like? Our own, as an example

Here is how the five steps work on Tember's glasses. Everything below is published on our compliance and test documents page:

  • Certificate: EU type-examination certificate CE-PC-260615-499-01-9A, for solar eclipse glasses as Category II PPE.
  • Notified body: CCQS Certification Services Limited, notified body number 2834.
  • Standard: EN ISO 12312-2:2015.
  • Models covered: C2026, B2026, G2026, P2026 and Y2026.
  • Dates: issued 17 June 2026; the document shows validity through 28 January 2031.
  • Responsible businesses: manufacturer Rezos LLC (USA); EU authorised representative and importer Nacnic Estudio SL in Zaragoza, Spain.
  • Check it yourself: enter the certificate number on the CCQS certificate verification page, and look up body 2834 in NANDO.

What this does and does not prove: the certificate records that the examined type passed EN ISO 12312-2. Keeping series production consistent is our responsibility under module C. A certificate from a well-known notified body is not, by itself, proof that every lot from every brand is fine: one of the models withdrawn in Spain in 2026 belonged to a brand whose paperwork also verified. That is why we also publish a separate independent laboratory report and say exactly what it covers. Our FAQ on what ISO 12312-2 means has more.

What do European authorities tell buyers to check?

  • Spain, Ministry of Consumer Affairs (August 2026): glasses must carry the CE mark, come with the EU declaration of conformity and have undergone an EU examination; buy from official channels, specialist shops or dealers recommended by scientific bodies. Its leaflet adds: a reference to EN ISO 12312-2:2015, the manufacturer or importer clearly identified, instructions and warnings, and a filter without scratches, breaks, bubbles or clear patches.
  • Spain, IGN: look for "EN ISO 12312-2:2015" and a genuine CE mark; "ISO 12312-1" alone means general-use sunglasses, not solar filters.
  • France, DGCCRF (July 2026): the CE mark on the product, the EN ISO 12312-2:2015 reference, the declaration of conformity with the product or online, instructions in French, manufacturer and importer details, no scratches. By late July 2026 it had already checked nearly 90 businesses.
  • Germany, BfS (Federal Office for Radiation Protection): the valid standard is DIN EN ISO 12312-2, the glasses must carry the CE mark, and sunglasses or welding goggles are no reliable protection.

The common thread: CE mark, the right standard, a named manufacturer, instructions, and an undamaged filter. The certificate trail is the extra step that tells you whether those markings are backed by a notified body.

Is welding glass an alternative?

Only the right shade, and it is not ISO 12312-2 eclipse eyewear. The AAS says a welding filter of shade 12 or higher transmits a safely tiny amount of sunlight, with shade 13 or 14 the "sweet spot"; NASA's 2017 eclipse safety guidance was stricter and asked for shade 14 or darker. The BfS says welding goggles are no reliable protection. If you don't know the shade number, don't use it; certified eclipse glasses are simpler. See how to use eclipse glasses safely.

Red flags and good signs at a glance

Red flag Good sign
ISO logo on the glasses, or "ISO certified" "EN ISO 12312-2:2015" printed as a standard reference
Only "ISO 12312-1", or no standard at all CE mark plus manufacturer's name and address
No manufacturer or EU importer named EU declaration of conformity in the box or at a stated web address
A "certificate" from a lab that is not a notified body, or a test report shown as a certificate EU type-examination certificate naming a notified body with a four-digit number
Certificate for different models, or out of date Certificate covers your model and is valid (at most five years)
Notified body not found in NANDO for PPE Body listed in NANDO under Regulation (EU) 2016/425; certificate verifiable online
Scratches, holes, light visible through the filter Uniform filter, only the Sun or a very bright lamp visible through it

Planning for 2 August 2027? Tember eclipse glasses are certified to EN ISO 12312-2:2015 and carry the CE mark, with the full certificate trail public. Packs run from 4 to 100 pairs. See the glasses, or for schools, clubs, hotels and town halls, our bulk eclipse glasses page. Where the eclipse is total and where it is partial: the 2027 path of totality, country by country.

Frequently asked questions

What does ISO 12312-2 mean on eclipse glasses?

It means the maker claims the glasses meet the international standard for filters for looking directly at the Sun: limits on visible, UV and infrared light, no defects, and required markings. In the EU the claim should be backed by an EU type-examination certificate from a notified body.

Is ISO 12312-2 the same as EN ISO 12312-2?

Yes, the technical content is the same. EN ISO 12312-2:2015 is the European adoption of ISO 12312-2:2015, published by national standards bodies with their own prefix, such as DIN in Germany. On glasses sold in the EU you will usually see the EN ISO form.

Can eclipse glasses be "ISO certified"?

No. ISO writes standards but does not test products or issue certificates, and its logo should not appear on products. Glasses can be tested to ISO 12312-2 by a laboratory and, in the EU, certified by a notified body.

Why is there no notified body number next to the CE mark on my eclipse glasses?

Because eclipse glasses are category II PPE. Under Regulation (EU) 2016/425 the notified body's number follows the CE mark only on category III PPE. For category II, the notified body is named on the EU type-examination certificate instead.

How can I check if an eclipse-glasses certificate is real?

Check that it is an EU type-examination certificate naming a notified body with a four-digit number, that it covers your model and is still valid, that the body is listed in the European Commission's NANDO database for PPE, and, if the body offers it, verify the certificate number on its website.

Can eclipse glasses be too dark?

Yes. ISO 12312-2 sets a minimum as well as a maximum light transmission, roughly equal to welding shade 15 at the dark end. Filters that are too dark tempt people to lift the glasses to find the Sun; Spain withdrew several models for this reason in 2026.

Is ISO 12312-2 being revised?

Yes. ISO says the 2015 edition is expected to be replaced by a new edition (at the final draft stage) within months, and the AAS says national bodies are voting on it in 2026. Until it is published, the 2015 edition applies.

Sources

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