"9H hardness" appears on virtually every tempered glass listing. Precisely because they all claim it, it is useless for choosing between them — and the number does not mean what most buyers assume.
The confusion is understandable. The Mohs scale taught in school runs from talc (1) to diamond (10). If 9H were a Mohs figure, a screen protector would sit almost at sapphire. It does not.
The 9H comes from a pencil hardness test, an industrial method for coatings. Leads of increasing hardness are drawn across the surface and the first one to leave a mark is recorded. The pencil scale runs from 9B (softest lead) to 9H (hardest). "9H" therefore means the protector withstands the hardest pencil in the set — nothing more.
Translated into Mohs, the tempered glass in these products sits at around 6. Far less impressive, and considerably more informative.
That 6 on Mohs explains what anyone who has taken a phone to the beach already knows. Quartz — the main constituent of sand and of a good share of household dust — sits at 7 on the Mohs scale. Harder scratches softer, so sand scratches the protector no matter what 9H figure is printed on the box.
The inverse is better news: keys and coins are alloys around 4 to 4.5. They do not scratch glass, and never did. The pocket-full-of-keys worry is a holdover from the era of plastic screens.
So a protector does not prevent the sand scratch — it takes the scratch instead of your screen. When it is marked, you replace a cheap component rather than living with a scarred display.
If a listing boasts only about 9H and mentions none of these, it is describing exactly what its competitors claim too, and staying quiet about what separates them.
Prices change daily, so the price and availability that count are always the ones shown on Amazon once you follow the link.
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Read the guide →No. It is the pencil hardness scale, running 9B to 9H, which measures which lead marks a coating. On the Mohs scale, which ends at 10 with diamond, the glass in these protectors sits at around 6.
Yes, against anything harder than it. Sand and dust contain quartz at Mohs 7, above glass. That is the scratch you will actually see; keys and coins are too soft to mark it.
Thickness, whether the adhesive covers the whole surface rather than just the edge, the quality of the oleophobic coating, and whether an installation frame is included. Those vary between products; 9H does not.
No. Thicker glass absorbs impact better but is more noticeable to the touch, is more likely to foul your case, and can interfere with an under-display fingerprint reader — particularly an ultrasonic one.