Solar Eclipse Glasses: How to Check a Pair Is Safe
The standard to look for, three checks you can run at home, what never replaces a genuine pair, and the partial eclipses still to come over the UK.
Which solar eclipse glasses are safe?
Safe solar eclipse glasses meet ISO 12312-2, the international standard for filters that let you look directly at the Sun, and the filter is undamaged. The UK Health Security Agency (UKHSA) gives the same rule: use only genuine eclipse glasses or handheld viewers with filters meeting ISO 12312-2:2015, buy from reputable retailers, and do not use a pair if you are unsure it is certified. Ordinary sunglasses are not adequate, however dark.
Anyone can print "ISO 12312-2" on a card frame. That is why the American Astronomical Society (AAS) adds a test of origin: buy from a listed manufacturer or one of its authorised dealers.
ISO 12312-2:2015
The label should carry the maker's name and address, viewing instructions and a permanent-eye-injury warning, in the language of the country of sale.
Intact filter
No scratches, punctures or tears, and the filter firmly held in its frame. A damaged pair goes in the bin.
Traceable seller
A listed manufacturer or its authorised dealer. A claim printed on the pack proves nothing by itself.
What ISO 12312-2 requires of the filter
| Property | Requirement |
|---|---|
| Visible light | At most 0.0032% transmitted, the level of a shade 12 welding filter (about 1 part in 31,000). The lower limit matches shade 15. |
| Ultraviolet | UVA and UVB transmittance no higher than the measured visible transmittance. |
| Infrared | At most 3%. |
| Uniformity | Visible transmittance uniform within 10% across the filter. |
| Pinholes | Metal-coated filters: no more than one pinhole of 200 µm or less in any 5 mm circle. |
| Fit | Large enough to cover both eyes of an adult, with a nasal cutout that fits a typical nose. |
| Label | Manufacturer name and address, viewing instructions, a warning of permanent eye injury, a warning to discard scratched, punctured or torn filters. |
Source: the AAS annotation of the standard, eclipse.aas.org. Compliance has to be confirmed by a laboratory approved by a recognised accrediting body, which is why the AAS keeps a list of manufacturers whose products were tested that way.
Lab testing matters because shelf products vary. When University of New South Wales researchers measured 43 commercially sold filters against the standard, all 43 met the UV and infrared limits but only 18 met the visible-light requirement; 24 were borderline. The authors argue the visible limits come from welding standards and propose a range of 0.00004% to 0.0012%. That is a proposal, not the current standard.
Four checks before you trust a pair
These come from the AAS. None of them proves a pair is safe, but a pair that fails any one should not be used.
Inspect the filter
Discard it if it is torn, scratched or punctured, or if the filter is coming loose from the frame.
Indoors
Put the glasses on and look around. You should see nothing except, perhaps, very bright lights, which look very faint. If you can make out furnishings or pictures on the wall, the filter is not dark enough.
Outdoors on a sunny day
Look around again. Only a faint reflection of the Sun off a shiny surface or a puddle should be visible.
A glance at the Sun
For under a second, you should see a sharp-edged round disk, comfortably bright against a dark background. It may look white, bluish white, yellow or orange.
What a pass means
The AAS says a pair that passes all three viewing tests is "probably" safe. If you are not fully confident, it suggests looking through the pair for no more than 2 or 3 seconds about every 5 minutes. A pair that fails: discard it or ask for a refund.
Why a CE or UKCA mark does not settle it
What the marks mean in Great Britain
For equipment covered by the PPE rules, gov.uk guidance says a manufacturer using self-declaration can affix either the UKCA or the CE marking, and that CE recognition now runs indefinitely. The manufacturer must also draw up a declaration of conformity that accompanies the product or says where to get it. A mark and a declaration are the maker's own statements. The AAS position is that a statement on a pack proves nothing without traceability. Voir aussi : When Is the Next Solar Eclipse?.
Counterfeits are not new
The AAS warns that some companies print the name of a listed manufacturer on their own products. In 2017, counterfeit glasses spread before the US eclipse; Amazon then required proof of accredited ISO certification for eclipse products and withdrew non-compliant listings. In April 2024 the Illinois Department of Public Health recalled brands that failed the standard (Wikipedia, Solar viewer).
Where to buy solar eclipse glasses in the UK
Sellers worth trusting
UKHSA tells readers to buy from reputable retailers and names Royal Museums Greenwich as one. The AAS no longer vets every reseller; it recommends buying direct from manufacturers or their publicly identified authorised dealers, and warns against online marketplaces and retailers cashing in on an eclipse. For Europe, it points to the Eclipse Seguro list run by OVAE. It also advises against buying from internet ads or search results.
Shops near you, supermarkets and free pairs
A pack on a high-street or supermarket shelf tells you nothing about the filter by itself. Read the label for the maker's name and address and the ISO 12312-2 reference, and run the indoor test in the shop: you should see nothing but very bright lights. Free pairs handed out by astronomers, clubs, university departments, museums or planetariums are usually traceable to a listed maker, so ask whose they are.
Buying for a school, a club or an event? Our wholesale eclipse glasses page covers bulk orders.
Can you make your own eclipse glasses?
No. NASA says homemade filters and ordinary sunglasses are not safe, because they transmit thousands of times too much sunlight. Dark does not mean safe: most of the damage comes from invisible infrared.
| What people try | Why it fails |
|---|---|
| Sunglasses, any darkness | They cut glare, which can make people look for longer (UKHSA), and still pass far too much sunlight. |
| 3D glasses | Royal Museums Greenwich: they do not protect your eyes. |
| Smoked glass, CDs, floppy disks, X-ray or colour film | Spain's national geographic institute (IGN) lists these as improvised filters and says colour and slide film are entirely unsuitable. |
| Camera neutral-density and polarising filters | On NASA's list of unsafe filters. |
| Welding glass | The AAS says shade 12 or higher, with 13 or 14 the best match, and only if you are certain of the shade number. Never an adjustable or auto-darkening helmet. |
| Eclipse glasses behind binoculars, a telescope or a camera | Concentrated sunlight can burn through the filter and injure the eye. A solar filter must sit at the front of the instrument. |
| A filter that screws into the eyepiece | The AAS calls these dangerous and says to discard them. |
Make a pinhole projector instead
Make a hole in a card, stand with your back to the Sun and let the image fall on paper held behind the card (Royal Museums Greenwich). Never look at the Sun through the pinhole (NASA). A colander, a perforated spoon or the gaps between tree leaves do the same job (UKHSA, AAS), and so does a "waffle" made by crossing your fingers.
Using glasses during a partial eclipse
- ✓Keep them on for every moment you look at the Sun. Only the brief totality of a total eclipse is safe without a filter; a partial eclipse has no such phase.
- ✓Inspect the pair before each use, not only the first time (NASA).
- ✓Supervise children who use solar viewers (NASA, AAS).
- ✓Do not count on cloud: cloud cover does not make it safe to look at the Sun (UKHSA).
- ✗Never look through a telescope, binoculars or camera optics while wearing eclipse glasses (AAS).
Reusing a pair from 12 August
The AAS annotation of the standard says modern viewers last up to 10 years if stored and maintained in good condition, and that printed three-year or three-minute warnings do not apply to ISO 12312-2 compliant viewers. The standard lets a maker state an obsolescence period on the label, so follow it if your pair has one. Scratched, punctured or torn: discard.
Partial eclipses still to come over the UK
| Date | What the UK sees | London |
|---|---|---|
| 12 August 2026 (past) | Partial, with the Moon covering around 90 to 96% of the Sun, at sunset (Royal Museums Greenwich) | - |
| 2 August 2027 | Partial, deepest in the south. Southampton about 44%, Glasgow about 28% (UK Eclipse) | 41.9%, 09:03 to 10:59 BST, maximum 10:00 |
| 26 January 2028 | Partial in the UK (annular in Spain and Portugal), ending at sunset | 50.4%, from 15:36 GMT, sunset at 16:38 |
| 2090 | Next total solar eclipse visible from the UK (Royal Museums Greenwich) | - |
London figures for 2027 and 2028 are from the Wikipedia eclipse tables (2028). Glasses stay on from first to last contact on all three partial dates. See our pages on the 2 August 2027 total eclipse, the 26 January 2028 annular eclipse and the full calendar of the next solar eclipses.
If you looked at the Sun without protection
After the 1999 total eclipse, the Royal College of Ophthalmologists reported around 70 cases of people with vision problems, and around 40% of them had looked for less than a minute (UKHSA). Damage is painless and the signs can come several hours later.
- !Blurred vision
- !A central blind or dark spot
- !Distorted vision
- !Reduced colour perception, or more sensitivity to light
Notice any of these? See an optometrist or doctor promptly and say you watched an eclipse. Some people recover over weeks or months; others are left with permanent visual impairment (Queen Victoria Hospital NHS Foundation Trust, citing the Royal College of Ophthalmologists).
Frequently asked questions
Can I reuse the eclipse glasses I bought for 12 August 2026?
Yes, if the filter is intact and the pair passes the checks above. The American Astronomical Society (AAS) says modern ISO 12312-2 viewers last up to 10 years when stored and kept in good condition, and that printed warnings to discard a pair after three years do not apply to compliant viewers. If your pair prints its own obsolescence period, follow it. Discard any pair with a scratch, puncture or tear.
Are very dark sunglasses safe for an eclipse?
No. UKHSA, the Royal College of Ophthalmologists, NASA and the AAS all say ordinary sunglasses are not adequate, however dark. They transmit many thousands of times too much sunlight, and by cutting glare they make it easier to keep looking.
How long can I look at the Sun through eclipse glasses?
The AAS says some packs print a three-minute limit that does not apply to ISO 12312-2 compliant viewers. If you are not fully confident in a pair, its advice is to look for no more than 2 or 3 seconds about every 5 minutes. A partial eclipse changes slowly, so there is no need to stare.
Can I make my own solar eclipse glasses?
No. NASA says homemade filters are not safe. Make a pinhole projector instead: put a small hole in a card, stand with your back to the Sun and let the image fall on paper behind it. Never look at the Sun through the pinhole.
Where can I buy solar eclipse glasses near me?
UKHSA advises buying from reputable retailers and names Royal Museums Greenwich as one. The AAS advises buying from listed manufacturers or their authorised dealers. For any shop or supermarket pack, check the maker's name and address and the ISO 12312-2 reference on the label, then run the indoor test before you pay.
Is a CE or UKCA mark enough to trust a pair?
No. A mark is the manufacturer's own declaration. The AAS points out that anyone can print a compliance statement on a pack and that some companies print a listed manufacturer's name on their own products. Check the ISO 12312-2 reference, where the pair came from, and the physical condition of the filter.