HEPA 13 and other filter grades explained

Air purifier filters are sold as HEPA 13, H14, E12 and more. These grades come from the European standard EN 1822. Here is what each class means and where the XR2's True HEPA 13 filter sits.

Where the grades come from

EN 1822 is a European standard that sorts high-efficiency air filters into classes by how much of the most penetrating particle size (MPPS) they capture. The MPPS is the particle size that a filter finds hardest to catch, so it is the toughest test.

The classes fall into three groups: EPA (E10 to E12), HEPA (H13 and H14) and ULPA (U15 to U17). Before the standard was revised in 2009, E10 to E12 were called H10 to H12, so you may still see those names.

Minimum efficiency by class

Class	Group	Minimum efficiency at MPPS
E10	EPA	85%
E11	EPA	95%
E12	EPA	99.5%
H13	HEPA	99.95%
H14	HEPA	99.995%
U15	ULPA	99.9995%
U16	ULPA	99.99995%
U17	ULPA	99.999995%

Integral efficiency values under EN 1822. Source: MANN+HUMMEL, EN 1822 filter classes.

What the numbers mean

An H13 filter must capture at least 99.95% of particles at the most penetrating size, so no more than 5 in every 10,000 of those particles get through. An H14 filter lets through no more than 5 in every 100,000.

For a home purifier, the filter grade is only part of the picture. How much air the purifier moves through that filter matters too; that is its CADR. See what CADR means.