The promethium mining rate is 1/(25,000 - (excavatorsOn * 2,000)).
| Excavators | Promethium rate | Average Promethium per day |
| 1 | 1/23,000 | 3.75 |
| 2 | 1/21,000 | 4.11 |
| 3 | 1/19,000 | 4.56 |
| 4 | 1/17,000 | 5.09 |
| 5 | 1/15,000 | 5.78 |
| 6 | 1/13,000 | 6.67 |
| 7 | 1/11,000 | 7.87 |
| 8 | 1/9,000 | 9.6 |
| 9 | 1/7,000 | 12.41 |
| 10 | 1/5,000 | 17.56 |