A numerical scale for classifying the consistency of lubricating greases, based on the ASTM D217 worked penetration at 25°C (77°F). NLGI Grades are also referred to as NLGI Consistency Numbers or NLGI Numbers. In order of increasing consistency (hardness):
| NLGI Grade | Worked Penetration Range, 25 °C (77 °F) |
| 000 | 445-475 |
| 00 | 400-430 |
| 0 | 355-385 |
| 1 | 310-340 |
| 2 | 265-295 |
| 3 | 220-250 |
| 4 | 175-205 |
| 5 | 130-160 |
| 6 | 85-115 |
Some grease suppliers use descriptions such as NLGI Number 1.5, which indicates that the grease is between NLGI Numbers 1 and 2.