HEPA class
retention (total)
retention (local)
E10 > 85% ---
E11 > 95% ---
E12 > 99.5% ---
H13 > 99.95% > 99.75%
H14 > 99.995% > 99.975%
U15 > 99.9995% > 99.9975%
U16 > 99.99995% > 99.99975%
U17 > 99.999995% > 99.9999%
HEPA filters, as defined by the DOE standard adopted by most American industries, remove at least 99.97% of airborne particles 0.3 micrometers (µm) in diameter. The filter's minimal resistance to airflow, or pressure drop, is usually specified around 300 Pa at its nominal flow rate.
The specification usually used in the European Union is the European Norm EN 1822:2009. It defines several classes of HEPA filters by their retention at the given most penetrating particle size (MPPS):
HEPA - Wikipedia, the free encyclopedia
So can take it that your N95 is E11, and N100/P100 masks are HEPA-13.