| Class name | Class limits | ≥0.1 µm | ≥0.2 µm | ≥0.3 µm | ≥0.5 µm | ≥5 µm | SI | English | m3 | ft3 | m3 | ft3 | m3 | ft3 | m3 | ft3 | m3 | ft3 |
| M1 | | 350 | 9.91 | 75.7 | 2.14 | 30.9 | 0.875 | 10.0 | 0.283 | | | M1.5 | 1 | 1,240 | 35 | 265 | 7.50 | 106 | 3.00 | 35.3 | 1.00 | | | M2 | | 3,500 | 99.1 | 757 | 21.4 | 309 | 8.75 | 100 | 2.83 | | | M2.5 | 10 | 12,400 | 350 | 2,650 | 75.0 | 1,060 | 30.0 | 353 | 10.0 | | | M3 | | 35,000 | 991 | 7,570 | 214 | 3,090 | 87.5 | 1,000 | 28.3 | | | M3.5 | 100 | | | 26,500 | 750 | 10,600 | 300 | 3,530 | 100 | | | M4 | | | | 75,700 | 2,140 | 30,900 | 875 | 10,000 | 283 | | | M4.5 | 1,000 | | | | | | | 35,300 | 1,000 | 247 | 7.00 | M5 | | | | | | | | 100,000 | 2,830 | 618 | 17.5 | M5.5 | 10,000 | | | | | | | 353,000 | 10,000 | 2,470 | 70.0 | M6 | | | | | | | | 1,000,000 | 28,300 | 6,180 | 175 | M6.5 | 100,000 | | | | | | | 3,350,000 | 100,000 | 24,700 | 700 | M7 | | | | | | | | 10,000,000 | 283,000 | 61,800 | 1,750 |
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