Minimum Efficiency Reporting Values (MERV)
ASHRAE Standard 52.2

Group
Number		 MERV
Rating		 E1
Average Particle
Size Efficiency (PSE)
0.3 – 1.0 Microns		 E2
Average Particle
Size Efficiency (PSE)
1.0 – 3.0 Microns		 E3
Average Particle
Size Efficiency (PSE)
3.0 – 10.0 Microns		 Average Arrestance
(ASHRAE 52.1)		 Minimum Final Resistance
(in. W.G.)
1 MERV 1
MERV 2
MERV 3
MERV 4		 –
–
–
–		 –
–
–
–		 Less than 20%
Less than 20%
Less than 20%
Less than 20%		 Less than 65%
65 – 69.9%
70 – 74.9%
75% or greater		 0.3m
0.3m
0.3m
0.3m
2 MERV 5
MERV 6
MERV 7
MERV 8		 –
–
–
–		 –
–
–
–		 20% – 34.9%
35% – 49.9%
50% – 69.9%
70% – 84.9%		 –
–
–
–		 0.6m
0.6m
0.6m
0.6m
3 MERV 9
MERV 10
MERV 11
MERV 12		 –
–
–
–		 Less than 50%
50% – 64.9%
65% – 79.9%
80% – 89.9%		 85% or greater
85% or greater
85% or greater
90% or greater		 –
–
–
–		 1.0m
1.0m
1.0m
1.0m
4 MERV 13
MERV 14
MERV 15
MERV 16		 Less than 75%
75% – 84.9%
85% – 94.9%
95% or greater		 90% or greater
90% or greater
90% or greater
95% or greater		 90% or greater
90% or greater
90% or greater
95% or greater		 –
–
–
–		 1.4m
1.4m
1.4m
1.4m

Notes

  1. ASHRAE Standard 52.2 tests are to be conducted at one of seven (7) air flow rates.
    • 118 FPM (.60 m/s)
    • 246 FPM (1.25 m/s)
    • 295 FPM (1.50 m/s)
    • 374 FPM (1.90 m/s)
    • 492 FPM (2.50 m/s)
    • 630 FPM (3.20 m/s)
    • 748 FPM (3.80 m/s)
  2. The air flow rate at which the filter was tested is included in the MERV rating (MERV-10 @ 2.5m/s)
  3. Filters with an E3 efficiency of less than 20% (MERV-1 through MERV-4) must also be tested for arrestance per ASHRAE Standard 52.1
  4. Final resistance must be at least twice the initial resistance at the test air flow rate. Or the values shown in the table above, whichever is greater.